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RICHARDS'

A C O N

REESE LIBRARY

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UNIVERSITY OF CALIFORNIA.,

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Accession? No. .^(f^l-vb Shelf No. ...

A TREATISE

R I C H A K D S

STEAM-ENGINE INDICATOR

DIRECTIONS FOE ITS USE.

BY CHARLES T. PORTER.

REVISED,

WITH NOTES AND LARGE ADDITIONS AS DEVELOPED BY AMERICAN

PRACTICE ; WITH A SUPPLEMENT, DESCRIBING THE LATEST

IMPROVEMENTS IN THE INSTRUMENTS FOR TAKING,

MEASURING, AND COMPUTING DIAGRAMS.

ALSO, AN APPENDIX,
CONTAINING USEFUL FORMULAS AND RULES FOR ENGINEERS.

BY F. W. BACON, M.E.,

OF THE AMERICAN SOCIETY OF CIVIL ENGINEERS.

OUKTH EDITION.

NEW YORK :

D. VAN NOSTRAND,
33 MURRAY STREET.

1883.

PREFACE.

IN introducing the Richards Improved Steam-
Engine Indicator, we desire to call the attention of
the numerous class who, as constructors, managers
or owners, are interested in the steam-engine, to
the advantages which it possesses. In the follow-
ing pages all necessary information is furnished
concerning the instrument and its application, and
such instruction is given to those who are not al-
ready skilled in the use of the Indicator, as will en-
able them to employ it to the best advantage.

The Indicator was invented by Watt. For some
time it was kept by him a secret, but became known
before his death, and to its use, now quite general,
we are more indebted than to anything else, for
the degree of excellence which the steam-engine
has attained. The employment of more rapid
velocities of piston, with higher pressures of steam,
and higher grades of expansion, which has become
so extensive and promises ultimately to be uni--
versal, has increased greatly the importance of the
Indicator ; since this is the only means as yet
known, by which the engineer can render himself

4: PREFACE.

familiar with the action of steam under these new
conditions. Unfortunately, every form of this in-
strument has hitherto failed in its application to
engines of this class. The long and tremulous
spring used in them was put in a state of violent
oscillation by the momentum of the piston and
attached parts, and the result was a serrated
figure, from which but little information could be
extracted ; so that, after a time, attempts to
employ the Indicator in this important and
rapidly enlarging field were qiiite abandoned.

Under these circumstances, the appearance at
the Great Exhibition of 1862 of the improved form of
this instrument, invented by Mr. Charles B. Richards,
an engineer of Hartford, Connecticut, U. S., may
not improperly be regarded as an event of some
importance. The action of this Indicator was
found to be quite perfect, under the severest tests
to which it could there be subjected, and recently
it has been still more thoroughly tried, on an
express engine on the London and South-Western
Railway, and its performance has more than real-
ized the expectations formed of it. Two instru-
ments, among the first manufactured by us, were
employed, with which nearly two hundred dia-
grams were taken, on a trip to Southampton and
back, at pressures varying from 80 Ibs. to 130 Ibs.,
at rates of motion varying from the slowest up to
260 revolutions per minute, giving a speed of 55
miles per hour, and at all points of cut-off ; and

PREFACE. 5

they were found uniformly to work with the same
steadiness at the highest velocity as at the lowest,
and at the earliest point of cut-off as at the latest.
Copies of a few of the diagrams are here given.

We do not claim for these Indicators superiority
on engines running at high velocities only, though
certainly it is there most apparent where others
will not answer at all ; but we believe also, for
reasons herein explained, that they will be found
in practice to be the only correct Indicators for en-
gines running at any speed, even the lowest.

We have only to add, that no pains have been
spared to attain, in the manufacture of these instru-
ments, the highest degree of accuracy and excel-
lence, and that if the directions here given are
attended to, their indications may be implicitly re-
lied on.

ELLIOTT BROTHERS.

PREFACE.

THE demand for an elementary treatise <on the
Richards Steam-Engine Indicator, together with
the solicitation of professional friends, has induced
me to undertake the preparation of the work.

The original and very excellent work of Mr. Por-
ter, now out of print, being principally an illustra-
tion of English engines and English practice, leaves
room for a work combining American engines and
American practice.

I have therefore used much of Mr. Porter's, and
added new matter and new diagrams — the result
of a large experience, extending over six years.

The new diagrams introduced were, with one or
two exceptions, taken by myself.

The diagrams taken November 14th, 1867, from
the locomotive No. 50, built by the " Taunton Lo-
comotive Works, " are believed to be the first ever
taken in this country from a locomotive when mak-
ing a regular trip with an express train.

It will be of interest to the American engineer
to compare them with those from an English loco-
motive, as shown in the work.

In order to make the work more useful to the
practical engineer, an Appendix has been added,
containing various formulas, which, during an ex-
perience of more than thirty years as a practical
engineer, have been collected, but never before
given to the public. The new rule to measure and
compute diagrams (page 42), will be found a very
expeditious and correct mode. The liabilities to
error being reduced as ten to one. It was brought
to my notice by Mr. Chas. E. Emery, engineer, New
York City. It is now for the first time published,
so far as I know.

The prime object has been to give nothing that
is not known by practical experience to be correct,
also to give it in a way that will be understood by
any one capable of filling the place of an engineer.

F. W. BACON.

BOSTON, October, 1873.

PREFACE TO THIRD EDITION.

A THIRD edition of this work is called for,
-*-\* showing that the Indicator is now being-
appreciated. Engineers are becoming educated in
its use ; it reveals to them many things which they
thought they knew, but find they didn't ; it has got
the attention of engine constructors ; it has inspired
the genius of the inventor and designer ; the speed
of the engine is increased, the immense ponderous
mass of matter formerly set in motion is largely re-
duced, space is economized, compounding is shown
to be a success and a necessity, coal and water bills
are being reduced to a minimum.

All these desirable things, it is safe to say, the
teachings of the Indicator has not only rendered
possible, but has accomplished de facto.

Still there is a wide margin yet to fill before its
office is accomplished.

Increasing the speed of the engine rendered an
improvement necessary in the Indicator, which our

x PREFACE: TO THIRD EDITION.

Supplement shows to have been admirably accom-
plished by Mr. Thompson.

The measurement and computation of diagrams
heretofore was a long, tedious, and unsatisfactory
work ; now the Planimeter has been produced, at a
price that can be reached by all, it has reduced the
time and labor to a few minutes, with the greatest
accuracy.

F. W. BACON, M. K,

No. 8 PEMBERTON SQUABE, BOSTON.

RICHARDS

IMFKOVED

STEAM-ENGINE INDICATOR.

THE NATURE AND USE OF THE INDICATOR.

THE Steam-Engine Indicator is an instrument
designed to show the pressure of steam in the
cylinder, at each point of the piston's stroke. It
does this in the following manner : A pencil,
moving up and down with the varying pressure of
the steam, draws a line on paper, which has a
motion backward and forward, coincident with
that of the piston. The paper is placed on a
drum, which, while the piston is advancing, is
caused to make about three-quarters of a revolu-
tion, by means of a cord connected with a suitable
part of the engine, and while the piston is rece-
ding, is brought back to its first position by the
reaction of a spring. The pencil is attached to a
small piston, moving without friction in a cylinder,
1*

10 RICHARDS' STEAM-ENGINE INDICATOR.

and the motion of which is resisted by a spring of
known elastic force.

TLe pressure of the atmosphere is always on
the upper side of this piston, and when the com-
munication with the cylinder of the engine is
closed, it is on the under side also ; and if then
the motionless pencil be applied to the moving
paper, it will draw a line which is called the
atmospheric line. When the commiTjiicatioii is
opened between the under side of this piston and
one end of the cylinder of the engine, the piston
will be forced upward by the pressure of the
steam, or downward by that of the atmosphere,
as the one or the other preponderates ; and if
now the pencil be applied to the moving paper, it
will describe, during one revolution of the engine,
a figure, each point in the outline of which will
show, by its distance above or below the atmos-
pheric line, the pressure in that end of the cylin-
der, when the piston was at the corresponding
point of its forward or return stroke. The spring
which resists the motion of the Indicator piston
is so proportioned in strength that a change of
pressure of one pound on the square inch shall
cause the pencil to move up or down a certain
fractional part of an inch.

The diagram thus described shows on inspection
tho following particulars, viz., what proportion of
the boiler-pressure is obtained in the cylinder ;
how early in the stroke the highest pressure ia

RICHARDS' STEAM-ENGINE INDICATOR. 11

reached ; how well it is maintained ; at what point,
and at what pressure, the steam is cut off ; whether
it is cut off sharply, or in what degree it is wire-
drawn ; at what point, and at what pressure it is
released ; in a non-condensing engine, whether it
is freely discharged, or what proportion of it re-
mains to exert a counter-pressure ; in a condens-
ing engine, the amount of the vacuum, and how
quickly, or how gradually it is obtained ; and in
both classes of engines, whether, before the com-
mencement of the stroke, there is any compression
of the vapor remaining in the cylinder, and if so,
at what point it commences, and to how high a
pressure it rises. From the diagram, the mean
pressure exerted during the stroke, to produce and
to resist the motion of the piston, may be ascer-
tained, and thus the engineer may come to l^now
accurately the amount of power required to over-
come the whole aggregate resistance on the engine,
and also, by taking separate diagrams for each, the
power required by each of the several resistances
or classes of resistance separately.* He may en-

* This we find of great use when called to determine (as
we often are) the power used by tenants. The landlord lets
power to his tenants ; it is fixed at a given price per horse-
power. The question arises, how much the tenant does use.
This is accurately determined. The practice is this: We take
several diagrams, one from each end of the cylinder, when
the engine is doing all the work, noting the number of revo-
lutions being made when each pair is taken. Should there

12 RICHARDS' STEAM-ENGINE INDICATOR.

deavor also to ascertain the causes of the various
features presented in the diagram, and thus to
learn the effect produced by this or that form or
arrangement of parts, and to detect any imperfec-
tion in their construction or action.

It must be borne in mind, that the Indicator
shows only the pressure at each point of the
stroke; to represent this faithfully is its sole office.
It tells nothing about the causes which have de-
termined the form of the figure which it describes.
The engineer concludes what these are, as the
result of a process of reasoning, and this is the
point where errors are liable to be committed.

be a difference of speed of the engine during the time of
taking these diagrams it is noted on each pair, and arranged
when worked up.

These diagrams and the result we mark "all on;" then we
stop tenant No. 1, throw off the belt that carries his work,
take say three pairs of diagrams, and work them up. Now, as
much as these are less than the average of those taken with
"all on," so much we charge tenant No. 1. We then put his
belt on and proceed with tenant No. 2, and charge him in the
same manner. Thus we proceed with all. In making up
our accounts for each, and adding them, we find the aggre-
gate will fall short of the gross of "all on." This is as it
should be, from the well-known fact that the friction of the
engine and intervening machinery decreases as the power
required decreases, and vice versa.

This amount of decrease or increase, as the case may be,
we have found to vary from 5 per cent, to 8 per cent, de-
pending on circumstances. Whatever it may be it should be
charged to the tenant.

RICHARDS' STEAM-ENGINE INDICATOR. 13

Conclusions which seem obvious sometimes turn
out to have been wrong, and the ability to form an
accurate judgment, as to the causes of the pecu-
liarities presented in a diagram, is one of the
highest attainments of an engineer.

The variety of diagrams given by different en-
gines, and by the same engine tinder different
circumstances, is endless ; and there is perhaps
nothing more instructive to the student of engi-
neering, as there is nothing more interesting to
the accomplished engineer, than their careful and
comprehensive study, with a knowledge of the mod-
ifying circumstances under which each one was
taken. Lines at first meaningless become full of
meaning; that which scarcely arrested his atten-
tion, comes to possess an absorbing interest; he
becomes acquainted with the innumerable variety
of vicious forms, and learns the points and degrees,
as well as the causes, of their departure from the
single perfect form; he becomes familiar with the
effects produced by different constructions and
movements of parts, and competent to judge cor-
rectly as to the performance of engines, and to
advise concerning changes, by which it may be
improved; he ceases to be a mere imitator of ma-
terial shapes, and learns to strive after the highest
excellence, and, at the same time, to comprehend
its conditions. No one at the present day can
claim to be a mechanical engineer who has not
become familiar with the use of the Indicator, and

14 RICHARDS' STEAM-ENGINE INDICATOR.

skilful in turning to practical advantage the varied
information which it furnishes.

This brief summary of the uses of the Indicator
would be incomplete without calling attention to
the importance of applying it to boilers, as a means
of testing the accuracy of the pressure-gauges, and
to pumps, for the purpose of ascertaining the causes
of any inefficiency in their action, and also to the
condenser and the air pump of condensing engines.

The diagram, No. 1, taken from one of the
engines of a well-known steamship,* is introduced
here to illustrate the action of the Indicator, as
just described.

The scale of the Indicator was twelve pounds to
the inch. The line A B is the atmospheric line, and
c D the line of perfect vacuum. The lines forming
the outline of the diagram will be designated, for
convenience of description, as follows : —

The line from a to 6, the admission-line.

6 to c, the steam-line.

" c to d, the line or curve of expansion,

" d to <?, the exhaust-line.

" e to /, the line of counter-pressure.

" / to a, the compression-line.

* The engines from which the diagrams here employed for
•illustration were taken, will not be mentioned, except in two
or three exceptional cases ; the object of this paper being, not
to publish the comparative performance of different engines,
but to give instruction to those who may require it, in the use
of the Indicator.

RICHARDS' STEAM-ENGINE INDICATOR. 15

The steam-line does not in fact end at c, but at
some unknown point beyond c. The diagram is divi-
ded by lines drawn perpendicular to the atmospheric
line into ten equal parts, and also by lines drawn
parallel with the atmospheric line at intervals of
five wounds pressure. The object of these is to
enable the engineer to observe more accurately the
nature of the diagram, and to ascertain the mean
pressure exerted during the stroke, the mode of
doing which will be explained hereafter. The line
<? g is the theoretical expansion curve drawn from
the point c.

. From an examination of this diagram, we con-
clude that the exhaust-port was covered at the point
/, of the return stroke, and the vapor remaining in
the cylinder was then compressed by the advance
of the piston to a density, at the commencement of
the forward stroke, of about five pounds above the
atmosphere. The port was then opened for admis-
sion, and the pressure instantly rose to fourteen
and a half pounds above the atmosphere. The
port being opened wider and wider, this pressure
was maintained behind the advancing piston to the
point c, at which it began to fall, at first very
slowly, from the gradual closing of the port by the
cut-off valve. The point at which the port was
covered cannot be identified. It was certainly, how-
ever, far beyond the point c, and strictly the steam -
line continues to the point of cut-off, however the
pressure may fall before that point is reached. At

16 RICHARDS' STEAM-ENGINE, INDICATOR.

the point d, the pressure had fallen by expansion to
two pounds above the atmosphere. Here the valve
began to open communication with the condenser,
and before the piston commenced its return stroke
the pressure on this side of it fell to nearly ten
pounds below the atmosphere, and almost imme-
diately after a vacuum of twelve pounds was formed ;
and when the return stroke was two-thirds accom-
plished, the counter-pressure suddenly fell half a
pound lower, and this vacuum was maintained
until the exhaust-port was closed at the point /.
We shall refer to this diagram again, when on the
subjects of calculating the power of the engine from
the diagram, and of working steam expansively.

OF TEUTH IN THE DIAGBA.M.

It is, of course, of the first importance that the
diagram given by the Indicator shall be true.
Causes of error appear at every point, and the de-
gree of falsity arising from them increases greatly
with an increase in the rate of revolution of tho
engine. It is not possible to be too critical in using
the Indicator, especially at high speeds; the errors
we are not conscious of are the ones sure to mis-
lead us.

The Conditions of a correct Diagram are — 1st,
that the movements of the paper shall coincide ex-
actly with those of the piston ; and, 2nd, that the

RICHARDS' STEAM-ENGINE INDICATOR. 17

movements of the pencil shall simultaneously and
precisely represent the changes of pressure in that
end of the cylinder to which the Indicator is
attached.

1st. Errors in the Motion of the Paper. — The com-
mon errors in communicating motion to the paper
are of two kinds — those which arise out of the
movements employed, and those which, when the
movements are correct, are occasioned by a high
velocity of the parts; but with proper care these
may all be avoided. We shall mention them in
detail presently, in connection with instructions for
applying the Indicator.

2d. Errors in the Motion of the Pencil. — These
are of a more serious nature. The spring may be
accurate, but its unavoidable length and weakness,
and its weight, joined to that of the piston
and other attached parts, and the distance through
which these must move, in order that the indica-
tions may be on a scale of sufficient magnitude,
render it impossible to obtain from engines which
run at any considerable speed, with any form of
Indicator hitherto in use, diagrams which can make
any claim to accuracy.

THE RICHARDS INDICATOR

Is constructed on a plan by which it is found that
these difficulties are quite avoided, and correct dia-

18 RICHARDS' STEAM-ENGINE INDICATOR.

grams are obtained under all circumstances. The
principal distinguishing features of this instrument
are a short and strong spring, a short motion of
piston and light reciprocating parts, combined with
a considerable area of cylinder, and an arrange-
ment of levers and a parallel motion, for multiply-
ing the motion of the piston in such a manner that
the diagram is described in the usual way and of
the ordinary size. The proportion between the
motion of the piston and that of the pencil is a
matter of discretion; that which has been adopted
is 1 to 4, and the steadiness with which the indica-
tion is drawn by these instruments, even at the
highest speeds of piston, leaves nothing to be de-
sired.

The diagrams numbered 2, 3, 4, 5, are fair sam-
ples of a large number taken from the locomotive
" Eagle," on the London and South- Western Rail-
way, in April, 1863. In three of them, the pencil
was held to the paper during a number of revolu-
tions ; in diagram No. 5 it passed over the paper
only once and a half. They are introduced here to
show the correct action of the instrument; we shall
have occasion to consider them also as illustrations
of working steam expansively.

General Construction of the Indicator. — The paral-
lel motion is made as compact as possible. For
this purpose, a lever of the third order is employ-
ed to multiply the motion, and the extremities of

KICHABDS" STEAM-ENGINE INDICATOR. 19

the line drawn by the pencil are permitted to have
a slight curvature, which considerably reduces the
length of the rods, and does not affect the use-
fulness of the instrument, the curvature at the
lower end being below any attainable vacuum,
while the extremity of the scale above is very
rarely employed.

The Indicators are made of a uniform size; the
area of the cylinder is one-half of a square inch,
its diameter being .7979 of an inch. The piston is
not fitted quite steam-tight, but is permitted to leak
a little; this renders its action more nearly friction-
less, and does not at all affect the pressure on
either side of it. The motion of the piston is f $ of
an inch, and the motion of the pencil, or extreme
height of the diagram, is 3| inches. The paper cyl-
inder is 2 inches in diameter, and the length of the
diagram may be 5 J inches, if this extent of motion
is given to the cord. The diagram is drawn by a
pointed brass wire on metallic paper. This is a
great improvement over the pencil ; the point lasts
a long time, cannot be broken off, and is readily
sharpened, and the diagram is indelible.* The
steam-passage has two or three times the area usu-

* We have used the metallic pencil with thf prepared me-
tallic paper. It works well, but the difficulty of procuring it,
together with its high cost, renders it objectionable. We use
heavy, unsized paper with a Faber No. 4 pencil ; we succeed
in getting good, distinct diagrams, with lines sufficiently fine
to measure correctly.

30 EICHABDS' STEAM-ENGINE INDICATOR.

ally given to it. The stem of the Indicator is coni-
cal, and fits in a corresponding seat in the stop-
cock, where it is held by a peculiar coupling, shown
in section in the accompanying cut of the Indica-
tor. This arrangement permits the Indicator to
be turned round, so as to stand in any desired po-
sition, when, the coupling being turned forward,
the difference in the pitch of the screws draws the
cone firmly into its seat; and when the coupling is
turned backward, the cone is by the same means
started from its seat. The leading pulleys may be
turned by some pressure, to give any desired direc-
tion to the cord, and will remain where they are
set. By these means the Indicator can be readily
attached in almost any situation.

The Springs. — In order to adapt this Indicator
for use on engines of every class, springs are made
for it to 4 different scales, as follows :

No. 16, which is graduated 16 Ibs. to the inch. 351bs.

No. 20, " " 20 " " " 56 "

No. 30, " " * 30 " " " 75 "

No. 40, " " 40 •« " " 105 "

All the above will also indicate 15 Ibs. below the
atmospheric line.

RICHARDS' STEAM-ENGINE INDICATOR. 21

PEACTICAL DIRECTIONS FOB APPLYING AND
TAKING CARE OF THE INDICATOR

I. OF ATTACHING THE INDICATOR.

When it is practicable, diagrams should be taken
from each end of the cylinder. The assumption
commonly made, that if the valves are set equal,,
the diagram from one end will be like that from
the other, will be shown by this instrument to be
erroneous. This is owing to the difference in the
speed of the piston at the opposite ends of the
cylinder, which is, at the outer end of a direct-
acting engine, from one-sixth to one-third greater
than at the crank end, the difference varying ac-
cording to the degree of angular vibration of the
connecting rod. In side-lever, or beam-engines,,
these proportions are reversed, and the speed of
the piston is greater at the upper end of the cylin-
der. Often, also, there is a difference in the
lengths of the thoroughfares, and in the lead, or
the amount of opening, or the point of closing ;
and many times the valves are supposed to be cor-
rectly set when this Indicator will show that they
are not. These, and many other causes, will make
a difference in the diagrams obtained from the op-
posite sides of the piston.

Pipes to be avoided. — The Indicator should be
fixed close to the cylinder, especially on engines
working at high speeds. If pipes must be usedr

22 RICHARDS' STEA.M-EXCUXE INDICATOR.

they should not be smaller than half an inch in
-diameter, and five-eighths in the bends, and as
;short and direct as possible. Any engineer can
;satisfy himself with this instrument that each inch
of pipe occasions a perceptible fall of pressure
between the engine and the Indicator, varying ac-
cording to its size and number of bends and the
speed of the piston. Diagrams have been known
to show, from this cause alone, forty per cent, less
pressure than was actually in the cylinder.

Where to connect the Indicator. — On vertical cylin-
ders, for tne upper end, the Indicator-cock is
usually screwed into the cover, where the oil-cup
is set, this being removed for the purpose. For
the lowar end, it is necessary to drill into the side
of the cylinder, at a convenient point in £he space
between the cylinder bottom and the piston, when
on the centre, and screw in a short bent pipe, with
A socket on the end to receive the Indicator-cock.
The Indicator can be used in a horizontal position ;
but it will be found much more convenient to put
in a bent pipe, and set it vertical. Sometimes it
will be necessary to drill in the side of the cylinder
at the upper end also, especially in double-cylinder
-engines having parallel motions, when the Indicator
cannot generally be set on the covers. Care must be
taken that the piston does not cover the hole when
on the centre. No putty is necessary to make
these small joints, and it should never be used, as

RICHARDS STEAM-ENGINE INDICATOR. 2£

it is liable to clog the instrument. If the screw fits-
loosely, a few threads of cotton wound round the
stem will prevent the escape of steam. Objections
are sometimes made to drilling a cylinder or its;
heads, for the reason that the borings as the drill-
passes through will be left in the cylinder and
likely to scratch it; this, with a little management,,
can be wholly prevented, by letting a little steam
on as the drill enters, which will blow it outwards.

On horizontal engines, the best place for the
Indicator is on the top or upper side, at each end;;
if it cannot be placed there, bent pipes may be
screwed into the covers or into the side of the
cylinder. In other respects follow the directions-
given for vertical engines. The Indicator should
never be set to communicate with the thorough-
fares. The current of steam past the end of the
pipe or the hole reduces the pressure in the instru-
ment, and the diagram given is utterly worthless,
as any engineer can readily ascertain by making
the experiment. On oscillating cylinders care must,
be taken to set the instrument in such a position
that the motion of the cylinder will not have the
effect to throw the pencil to and from the paper.

The stopcock being screwed firmly to its place,
screw the Indicator down to its seat, turning it to
the most convenient position, and make it fast by
turning the coupling; then move the guiding pul-
leys to their proper position to receive the cord,,
and the instrument is in readiness for use.

34: RICHARDS STEAM-ENGINE INDICATOR.

II. OF GIVING MOTION TO THE PAPER.

Tiie Drum the best Means. — The revolution of a
drum is probably the most correct as well as con-
venient method of giving motion to the paper. It
may be supposed that a flat slide, worked by posi-
tive means, would have a perfectly accurate motion;
but, in fact, at high velocities, where alone any
trouble is met with, the difficulties involved in its
use are more troublesome than those presented by
the cylinder. In most cases the connecting-rod
must necessarily be somewhat long; it must not
tremble, or the line on the paper will be tremulous,
:and the weight required for stiffness, joined to the
weight of the slide, causes a momentum, which, if
the rod is worked by a vibrating arm, will give fo
the paper, on each centre, a motion opposite to
that of the piston of the engine ; and precisely at
these points it is of the greatest consequence that
the two motions shall coincide.

In the use of the 'cylinder at any speed, the ques-
tion of obtaining a positive motion, if there is no
-elasticity in the cord or the parts to which it is
-connected, is simply one of proportion between the
momentum of the revolving parts and the strength
of the spring by which this is resisted. In this In-
dicator these parts are made as light as possible
-consistently with other requirements, and the
spring is of such strength that they may be reci-
procated from 250 to 300 times per minute, without

RICHARDS' STEAM-ENGINE INDICATOR. 25

any increase in the length of the diagram, and of
course, therefore, without any error in the motion.
There is no difference in the construction of these
Indicators in this respect, it being intended that
every instrument shall be applicable to any engine.

From what Points to derive the Motion. — This may
be taken from any part of the engine which has a
motion coincident with that of the piston. For a
beam-engine a point on the beam, or beam-centre,
or on the parallel-motion rods where these are em-
ployed, will give the proper motion; but care must
be taken that the cord be so led off, that when the
engine is on the half stroke it will be at right angles
to whatever gives it motion (a requirement too
often omitted) ; afterwards its direction of motion
may be changed as required, always taking care,
however, to use as few carrying pulleys as possible,
and the shortest possible cord, which should be of
linen, size No. 3 ; it should be well stretched by
suspending a weight to it for several days.

In some cases it is most convenient to take the
motion from a point on the end of the revolving
shaft ; this is frequently the case on horizontal en-
gines, working at high speeds, because then the
motion does not need to be reduced. Exact accu-
racy cannot be got in this way, however, without
-employing a moving slide, and connecting it with
the pin in the end of the shaft by a rod or cord of
such length that its angular vibration shall be the
2

26 RICHARDS' STEAM-ENGINE INDICATOR.

same as that of the connecting-rod. This will be
found generally a troublesome matter; and the en-
gineer will probably prefer in most .cases to disre-
gard the error resulting from its omission — which
is, that the motion of the paper will be more near-
ly equal at the two ends of the stroke, being slower
than that of the piston at the one end, and faster
at the other. The crank or pin from which the
cord receives its motion must be on its centre re-
latively to the direction of the cord, whatever that
direction may be, precisely when the crank of the
engine is on Us centre. If this requirement is not
carefully attended to, the diagram will be worth-
less.

Q-enerally, on horizontal engines, the motion of
the paper is taken from the cross-head. In an
engine-room, a strip of board may be suspended
from the ceiling, or carried off horizontally in such
a manner as to permit it to swing backward and
forward edgeways by the side of the guides, and
motion may be given to it by a pin, secured firmly
to the cross-head, and projecting through a slot in
the board, in which it should fit nicely to prevent
lost time on the centres. To save drilling and
defacing the cross-head to insert a pin, we use a
clamp made fast to the cross-head or some of its
appendages by a set screw ; a projecting pin plays-
in a slot in the board, or if preferred, a short con-
necting rod may be used to make the connection.
The board must hang plumb when the piston is in

RICHARDS' STEAM-ENGINE INDICATOR. 27

the middle of its stroke, or if horizontal at right
angles. The cord may be connected to this
strip of board at a point sufficiently near to its
point of suspension to give the required reduction
of motion for the paper, and must be led off in a
horizontal direction, and then over one or more
pulleys in any required direction to the Indicator.
At high speeds, however, pulleys should be avoided.
On portable engines, the motion may be attained in
the manner just described, the lever swinging from
a pin supported in a standard about two feet in
height, set on one of the guide-bars.

On locomotives having outside connections, the
motion must be taken from the cross-head. It is
indispensably necessary to use only a short direct
•cord, free from elasticity, and connected to a point
the motion of which is reduced from that of the
cross-head by positive means. Care must be taken
also so to proportion the parts employed for this
purpose, that the point at which the cord is con-
nected shall have a positive motion without any
fling, a matter not by any means free from difficulty
at 250 revolutions per minute. A rock-shaft,
turning in bushings, supported by two angle iron
standards, precisely over the mid-position of that
point of the cross-head from which the motion is
derived, affords perhaps the best means of redu-
cing the motion. A long-arm is worked by the
cross-head and a short-arm gives motion to the
cord. The short-arm must be keyed in such a po«

28 RICHARDS' STEAM-ENGINE INDICATOR.

sition that when the piston is in the middle of its
stroke it will stand at right angles with the direc-
tion of the cord, whatever that may be. The di-
rection of the cord may form any necessary angle
with the horizontal line, but must be at right
angles with the rock-shaft.

On locomotives having inside connections, and
a single pair of driving-wheels, where it is practi-
cable, it will be found to be the better way to take
the motion from a pin set in the end of the shaft,
and to communicate it by a connecting-rod to a
point convenient for attaching the cord. The parts
should be all substantially made; the momentum of
the connecting-rod will be perfectly resisted by the
pin.

On oscillating engines, the motion may be taken
from the brasses at the end of the piston-rod. If
the stroke is long, it is sometimes difficult to re-
duce this motion to that required for the paper, and
in such cases it is necessary to Jbake the motion
from an eccentric on the main shaft, to a point as
near as possible to the trunnion, and thence to
communicate it to the Indicator. In all these con-
nections, it is of the first consequence that there be
no lost time, which will require to be made up on
every centre, and will thus cause the paper to stand
still while the piston is moving.

Pulleys of different diameters on the same spin-
dle have often been used as a means of reducing
the motion from that of the cross-head, but we do

RICHARDS' STEAM-ENGINE INDICATOR. 29

not recommend them ; at high speeds it is very
difficult to make them answer. The experience of
the careful operator will teach him to guard against
the various causes of error here mentioned, and
•others which will arise in the great diversity of situ-
ations in which the Indicator is used, and the
effects of which are the more mischievous because
often the diagram itself furnishes no means of de-
tecting them. The mathematician will perceive
that perfect accuracy of motion is attained by only
a very few of the methods here suggested. Most
of them are only approximately accurate, but they
are the best which can be readily employed, and
the errors which they involve are too slight to be
of practical moment. For the professional engi-
neer, of course, directions are unnecessary.

IIL HOW TO TAKE A DIAGRAM.

To fix the Paper. — Take the outer cylinder off
from the instrument, secure the lower edge of the
paper, near the corner, by one spring, then bend
the paper round the cylinder, and insert the other
<x>rner between the springs. The paper should be
long enough to let each end project at least half an
inch between the springs. Take the two project-
ing ends with the thumb and finger, and draw the
paper down, taking care that it lies quite smooth
and tightj and that the corners come fairly together,
and replace the cylinder.

30 RICHARDS' STEAM-ENGINE INDICATOR.

To connect the Cord. — The Indicator having been
attached, and the correct motion obtained for the
drum, and the paper fixed, the next thing is to see
that the cord is of the proper length to bring the
diagram in its right place on the paper — that is,
midway between the springs which hold the paper
on the drum. In order to connect and disconnect
readily, the short cord on the Indicator is furnished
with a hook, and at the end of the cord coming*
from the engine, a running loop may be rove in a
thin strip of metal, in the manner shown in the
following cut, by which it can be readily adjusted

to the proper length, and taken up from time to
time, as it may become stretched by use. On high-
speed engines, it is as well, instead of using this, to
adjust the cord and take up the stretching, as it
takes place, by tying knots in the cord. If the cord
becomes wet arid shrinks, the knots may need to be
untied, but this rarely happens. The length of the
diagram drawn at high speeds should not exceed
four and a half inches, to allow changes in the length
of the cord to take place to some extent, without
causing the drum to revolve to the limit of its mo-
tion in either direction. On the other hand, the
diagram should never be drawn shorter than is
necessary for this purpose.

lUCHARDS' STEAM-ENGINE INDICATOR. 31

To take the Diagram. — Everything being in readi-
ness, turn the key of the stopcock to a vertical po-
sition, and let the piston of the Indicator play for
a few moments, while the instrument becomes
warmed. Then turn the key horizontally to the
position in- which the communication is opened
between the under side of the piston and the
atmosphere, hook on the cord and draw the atmos-
pheric line. Then turn the key back to its vertical
position, and take the diagram. When the key
stands vertical, the communication with the cylin-
der is wide open, and care should be observed that
it does stand in that position whenever a diagram
is taken, so that this communication shall not be in
the least obstructed.

To apply the pencil to the paper, take the end of
the longer brass arm with the thumb and forefin-
ger of the left hand, and touch the point as gently
as possible, holding it during one revolution of the
engine, or during several revolutions if desired.
There is no spring to press the point to the paper,
except for oscillating cylinders; the operator, after
admitting the steam, waits as long as he pleases
before taking the diagram, and touches the pencil
to the paper as lightly as he chooses. Any one, by
taking a little pains, will become enabled to per-
form this operation with much delicacy. As the
hand of the operator cannot follow the motions of
an oscillating cylinder, it is necessary that the point
be held to the paper by a light spring, and instru-

32 RICHARDS' STEAM-ENGINE INDICATOR.

ments to be used on engines of this class are fur-
nished with one accordingly.

Diagrams should not be taken from an engine
until some time after starting, so that the water
condensed in warming the cylinder, etc., shall
have passed away. Water in the cylinder in ex-
cess always distorts the diagram, and sometimes
into very singular forms. The drip-cocks should
be shut when diagrams are being taken, unless the
boiler is priming. If when a new instrument is
first applied the line should show a little evidence
of friction, let the piston continue in action for a
short time, and this will disappear.*

As soon as the diagram is taken, unhook the
cord; the paper cylinder should not be kept in
motion unnecessarily, it only wears out the spring,
especially at high velocities. Then remove the
paper, and minute on the back of it at once as
many of the following particulars as you have the
means of ascertaining, viz : —

The date of taking the diagram, and scale of the
Indicator.

* Thus, by the motion of the pencil up and down, and the
paper from right to left, and left to right, we transfer the
pressure of the steam and vacuum (if there be any), and the
movement of the piston to the paper, giving us a map or dia-
gram of the action required to move the load at any and all
points of the stroke, from which the power exerted may be
cc mputed and the condition of the internal action seen.

RICHARDS' STEAM-ENGINE INDICATOR. 33

The engine from which the diagram is taken,
which end, and which engine, if one of a pair.

The length of the stroke, the diameter of the
cylinder, and the number of double strokes per
minute.

The size of the ports, the kind of valve employed,
the lap and lead of the valve, and the exhaust lead.

The amount of the waste-room, in clearance and
thoroughfares, adds to the length of the cylinder.

The pressure of steam in the boiler, the diame-
ter and length of the pipe, the size and position of
the throttle (if any), and the point of cut-off.

On a locomotive, the diameter of the driving-
wheels, and the size of the blast orifice, the weight
of the train, and the gradient, or curve.

On a condensing-engine, the vacuum by the
gauge, the kind of condenser employed, the quan-
tity of water used for one stroke of the engine, its
temperature and that of the discharge, the size of
the air-pump and length of its stroke, whether
single or double acting, and, if driven indepen-
dently of the engine, the number of its strokes per
minute, and the height of the barometer.

The description of boiler used, the temperature
of the feed-water, the consumption of fuel and of
water per hour, and whether the boilers, pipes, and
engine are protected from loss of heat by radiation,
and if so to what extent.

In addition to these, there are often special cir-
cumstances which should be noted.
2*

34 RICHARDS' STEAM-ENGINE INDICATOR.

IV. HOW TO KEEP THE INDICATOR IN ORDER.

Having the attachments made; before we admit
steam to the instrument, we open the cocks and
blow through the connections to clear them from
any foreign matter, that it may not enter and
injure the instruments.

The Indicator will not continue to work well, un-
less it is kept in good order. When used, it gene-
rally becomes filled with water, which will rust and
thus weaken the spring, and the steam often con-
tains impurities and grit, a portion of which ia
lodged in it. After the Indicator has been used,
and before putting it up, unscrew the cover of the
cylinder case, and draw off the upper ferule, with
the pencil movement and the piston and spring at-
tached, empty the water from the cylinder case,
carefully clean and dry all the parts, and replace
them, lubricating the cylinder with a few drops of
oil which is entirely free from gum.* The cylin-

* The oil is very important; it should be of the purest kind,
free from gum and all foreign matter. The porpoise oil we
have found to answer all the requirements ; it has wonderful
ability to resist the action of steam and water. We have
found the cylinder well lubricated after having taken a hun-
dred diagrams. It has equal merit in preventing corrosion;
hence it should be used on the springs, piston-rod, and arms.
It costs high, but a small bottle of it will, if properly used,
last for years. It can be obtained of any first-class clock-
maker or dealer in clock materials. *

RICHARDS STEAM-ENGINE INDICATOR. 3.^

der is not to be removed from the case under any
circumstances; the operation above directed gives
complete access to it.

Sometimes the surfaces of the piston and cylinder
become scratched or roughened by impurities in
the steam, which will be detected at once in the
diagram by the unsteadiness of the line. If this
shows the existence of any obstruction to the per-
fectly free action of the Indicator, take the instru-
ment apart, as for cleaning ; take out the two
screws at the top of the piston-rod connecting it
with the pencil movement, and unscrew the spring
from the piston and the cover; then replace the
piston in the cylinder, after cleaning and lubri-
cating them; screw on the cover to guide the stem,
and rub the piston up and down in the cylinder,
at the same time revolving the stem between the
thumb and finger. The surfaces will quickly wear
each other smooth ; no grinding or polishing
material should be used; the piston should be taken
out once or twice during the operation, and the
surfaces cleaned. The piston, if dry, ought to drop
perfectly free from every position. Before re-
placing, lift the levers, and let them fall, to see if
their action also is entirely free. Then replace
everything, taking care to screw the heads of the
spring firmly up to the piston and cover. Before
putting the piston in the cylinder, revolve it be-
tween the thumb and finger, to ascertain if the
pins connecting it with the pencil movement turn

36 RICHARDS' STEAM-ENGINE INDICATOR.

quite smoothly in the groove at the end of the
stem. The paper cylinder requires to be lubri-
cated occasionally with a drop or two of pure oil,
applied at the end of the arbor, also the leading
pulleys and the joints of the pencil movement.

V. HOW TO CHANGE THE SPRINGS.

The directions already given for taking the in-
strument apart, for the purpose of smoothing the
surfaces of the cylinder and piston, are sufficient
also for changing the spring. Merely introduce
another, instead of replacing the one removed.
The lengths of the springs for the different scales
are so proportioned to each other, that the pencil
will always come to the proper position for drawing
the atmospheric line. Be careful that the heads
are screwed up firmly to the piston and cover.

The spring, which gives reaction to the paper
cylinder, is liable to break after considerable use,
especially on engines running at high speeds ;
for which reason this cylinder should never be left
to run unnecessarily. When this happens, a new
spring can be readily inserted, as follows. Set the
Indicator on the engine; if there is no other con-
venient means for holding it firmly, remove the
cover of the spring case and the broken spring;
then take out the screw, and remove the brass ring
from the arbor. Screw the new spring to the
brass ring, replace this on the arbor, and set the

RICHARDS' STEAM-ENGINE INDICATOR. 37

screw firmly up to the head. Then coil the spring
into the case, and hook the end on the rim ; see
tnat it is coiled in the same direction with the cord.
If the spring has not sufficient strength to keep the
cord quite tight, another coil must be given to it,
but it should not be coiled any tighter than is ne-
cessary for this purpose.

HOW TO ASCERTAIN THE POWER EXERTED BY
THE ENGINE.

The custom was introduced by Watt, and has
since been generally followed in England, to desig-
nate the size of engines in measures of " horse
power." Watt ascertained by experiment that the
power of London draught horses, exerted with ordi-
nary continuance, was to lift 33,000 Ibs. one foot in
one minute, and this is now employed, wherever
English measurements are used, as the unit of
measurement of the actual power of steam engines.

The Indicator furnishes one of the data for ascer-
taining the power exerted by the steam-engine,
namely, the mean or average pressure of steam
during the stroke, on each square inch of the
piston ; or, more accurately, the excess of pressure
on the acting side of the piston to produce motion,
over that on the opposite side to resist it. This
being multiplied into the whole number of square
inches, and the product by the mean or average
speed of the piston, in feet per minute, gives the

38 RICHARDS' STEAM-ENGINE INDICATOR.

total number of pounds of force acting through one
foot in a minute, which are called foot pounds, and
by dividing this by 33,000, which is the unit for a
borse power, we obtain the gross power of the
engine in actual horse powers.

In order to ascertain the effective power, how-
ever, there must be deducted from this the friction
of the engine, or the power required to drive the
engine alone at the same speed, which, except in
the case of vessels with the wheels submerged, the
Indicator generally enables us to ascertain ; and
also the increase in this friction which arises when
the resistance is being overcome, which the Indi-
cator does not show. The amount of this latter is
not generally known with any accuracy ; but we
know that the percentage of loss from this cause
diminishes as the size of the engine is enlarged,
because the increase in the motion of the surfaces
in contact is much slower than the increase in the
area of the piston, and also that it varies according
to the nature of the lubricating material employed,
and the degree of completeness attained in the
separation of the surfaces by means of it. Five
per cent, is usually allowed for this increase of
friction; but it may, in fact, be considerably more
or less than this. On small engines, the friction-
brake can be applied, to show the amount of effec-
tive power exerted, and a comparison of this with
the gross power, and with the friction of the engine
alone, as shown by the Indicator, will exhibit the
increase of friction occasioned by different amounta

RICHARDS' STEAM-ENGINE INDICATOR. 3D

of resistance, and show the value of different lubri-
cants, and the utility of extended wearing surfaces.
We will now describe the mode of ascertaining
from the diagram the mean pressures on the oppo-
site sides of the piston, in condensing and in non-
condensing engines. For this purpose, divide the
diagram into any desired number of equal parts,
by lines drawn perpendicular to the atmospheric
line. Sometimes these divisions are made very
numerous; but the usual practice is to make ten,
which number is probably sufficient, unless great
accuracy is desired, when twenty divisions may be
made. A convenient instrument for facilitating
this operation, saving time, and insuring accuracy,
is furnished with these Indicators. It consists of a
parallel ruler, of eleven bars of thin steel, and a
small square. The perpendiculars are first drawn
by the square at each end of the diagram, when,
the outer edge of bar No. 1 being brought to the
beginning, and the inner edge of bar No. 11 to the
termination of the stroke, the dividing lines are
drawn with a sharp-pointed pencil. If twenty
divisions are desired, the intermediate lines for this
purpose will also be readily drawn by means of
this instrument, points being first marked in the
middle of the outer divisions. It is an excellent
practice to divide the diagram also by lines drawn
parallel with the atmospheric line, into equal
divisions, each representing a certain number of
pounds pressure, generally five or ten, and num-

40 RICHARDS' STEAM-ENGINE INDICATOR.

bered on the margin according to the scale of the
Indicator ; by which means the engineer is able to
observe much more accurately the general nature
of the diagram. The same instrument may be
employed for this purpose.

On diagrams from condensing engines, the line of
perfect vacuum should be drawn at the bottom,
and the line of the boiler pressure, as shown by the
gauge, at the top.* The line of perfect vacuum
varies in its distance from the atmospheric line, or,
more correctly, the latter varies in its distance
from the former, according to the pressure of the
atmosphere, as shown by the barometer, from
13 . 72 Ibs. on the square inch when the mercury
stands at 28 inches, to 15 . 19 Ibs. when it stands at
31 inches (vide Table II.); and it should be drawn
according to the fact, if this can be ascertained.
The engineer should always have a good aneroid
in his pocket. The pressure of the atmosphere is
usually reckoned at 15 Ibs., which, as a general rule,
is too high, being correct only when the barometer
stands at 30.6 inches ; but the error is unimpor-
tant, and it is very convenient to avoid the use of
a fraction, and to say that 30 Ibs., 45 Ibs., 60 Ibs.,

* When accuracy is required, the steam-gauge should be
tested by the Indicator, which may be done by stopping the
engine on the centre, opening the steam-valve, and letting
the full pressure on the instrument; when the indications of
the two instruments may be compared and noted.

and so on, represent 2, 3, 4, 5, 6 atmospheres of
pressure.

The principal object of knowing the exact pres-
sure of the atmosphere is, to ascertain the duty
performed by the condenser and air-pump. The
temperature of the discharge being known, the
pressure of vapor inseparable from that tempera-
ture is also known (vide Table No. HI.), and this
being deducted from the actual pressure of the
atmosphere, the remainder is the total attainable
vacuum at that temperature.

The areas of the diagram above and below the
atmospheric line are usually calculated separately,
to ascertain how effectually the resistance of the
atmosphere is removed from the non-acting side of
the piston, by those parts of the engine whose func-
tion this is. In case of engines working very ex-
pansively, however, the expansion curve crosses
the atmospheric line, and sometimes at an early
point of the stroke, as in diagram No. 10. In such
cases, the whole space between the atmospheric
line and the line of counter-pressure should be
credited to the condenser and air-pump ; not, of
course, to be considered in estimating the power
exerted, but for ascertaining the degree of economy
in the consumption of steam, which depends greatly
on the amount of vacuum maintained.

The lines having been accurately drawn as above
directed, ascertain, by careful measurement with
the scale, the mean pressure in each division, be-

42 RICHARDS' STEAM-ENGINE INDICATOR.

tween the atmospheric line and the upper line of
the diagram, until this crosses the former, if it does
so; add these together, and point off one place cf
decimals, or divide their sum by the number of
divisions, if there are more than 10, and the quo-
tient will be the mean pressure above the atmos-
phere during the stroke. Then repeat the process
for the area between the atmospheric line, or the
expansion curve after it has crossed this line, and
the lower outline of the diagram. Add the two
mean pressures so ascertained together, then find
in Table No. I. the number of square inches in the
surface of the piston, if you know the diameter,
and multiply the pressure on one square inch by
the number of square inches, and the product by
the mean velocity of the piston, in feet per minute,
and divide by 33,000, and the quotient will be the
gross amount of horse-power exerted ; or the
power represented by the two areas of the dia-
gram, above and below the atmospheric line, may
be calculated separately.

[Since the publication of the First Edition, my attention
has been called to an improved method of measuring the dia-
gram which is more expeditious and less liability to error. ]

Thus, your diagram is divided into equal parts as
usual — say 10. Now, we take a narrow 'slip of paper,
or what is better, card-board that is thin and smooth;
this we place across the diagram as we would the
scale, letting the end of it be exactly over the base
line ; then with a sharp-pointed knife prick the slip

EICHARDS' STEAM-ENGINE INDICATOR. 43

40*

exactly over the line opposite the base (steam-line),
advance the slip to the next division, and carrying
the point made by the knife to the base line, then
remove the knife and make another prick exactly
over the line opposite. Repeat the movement until
you have measured each space ; then make a mark
with your pencil. Now, with a rule, you measure
the distance from the end of the slip to your pencil
mark ; we will assume that it is 6J inches. Now, as
you have measured 10 spaces, to get the average, we
divide it by 10 ; thus, 6J expressed decimally is 6.25.
This, divided by 10, is equal to .625.

Now the scale of the diagram we will assume to be
40 to one inch. We then multiply .625 by the scale,
which we have assumed to be 40, and we get the fol-
lowing result as an average pressure per square inch :

.625
40

25.000 Ibs. pressure.

Expressed in arithmetical signs, it is

6.25 -=- 10 = .625 x 40 = 25.000.

Should there be more or less than 10 divisions of
the diagram, divide by the number, whatever it is.
Should the scale of the instrument be other than 40,
then multiply by the number, whatever it may be.

This mode is much less liable to error than the
ordinary mode ; in fact, it reduces the liability as ten
to one. It is more expeditious, in so much as it saves
the additions of a long column of figures.

The space between the steam line and the line of
boiler pressure shows how much the pressure is

44: RICHARDS' STEAM-ENGINE INDICATOR.

reduced in the cylinder by throttling, or by the in-
sufficient area of the ports, proper allowance being
made for the difference of pressure necessary to
give the rapid motion to the steam, and that be-
tween the line of counter-pressure and the line of
perfect vacuum shows the amount of resistance to
the motion of the piston.

In illustration of the foregoing directions, let it
be required to find the effective power exerted by
the pair of engines, from the upper end of one of
which diagram No. 1 was taken, the diameter of
cylinder being 95", the stroke of the piston 10', and
the number of revolutions 15 per minute. We will
assume that the other engine would have given the
same diagram, which is possibly correct, and also
that the lower ends of the cylinders would have
given the same, which is probably quite incorrect,
because in side-lever, or beam engines, the speed of
the piston at the lower end is slower, and therefore
probably the pressure obtained is greater, than in
the upper end, the motion of the valves being the
same.

The mean pressure of steam above the atmosphere

was 9.82 Ibs.

The average vacuum was 11 .4.6 "

Total excess of pressure above the resistance was. 21.28 "

The better mode of calculation in all cases is, to
obtain first the number of horse-powers for 1 Ib. to
mean pressure on the square inch, as follows :

RICHARDS* STEAM-ENGINE INDICATOR. 45

Multiply the number of square inches in the

surface of the piston 7088 . 2

By the speed of the piston in feet per minute. 300

33. (000)2126(460. 0(61 44
198
146
132
144
132
"126

Which is the number of horse-powers exerted, for
each pound of pressure during the stroke on 1 square

inch of the piston 64.44

To obtain the gross power we multiply this by the

average pressure per square inch on the piston 21 .28

"51552

• 12888

6444
12888
Gross horse-powers exerted in one engine .... 1371 .2832

To obtain the effective power we must ab-
stract from the multiplier 21 . 28 Ibs.

The pressure required to run the engine
alone, which in so large an engine
would probably not exceed 1 .00 Ib.

And the increase in this pressure required
to overcome the increased friction when
the resistance is being overcome, say 5

per cent =1.06 "

2.061ba

Effective pressure on each square inch .... 1& . 22 "

Which multiplied by 64.44

7688
7688
7688
11532

Gives amount of effective horse-power ... 1238.5368
Which multiplied by 2

Gives 2,477.0 horse-
power as the effective power of the engines.

4(5 RICHARDS' STEAM-ENGINE INDICATOR.

It will be observed that, by the above mode of
calculation, we obtain for any engine, the speed of
piston continuing the same, a constant number,
which, multiplied by the mean pressure on a square
inch, gives at once the amount of horse-power
exerted at any time.

On diagrams from non-condensing engines, the line
of boiler pressure should be drawn at the top, and
it is well to draw the line of perfect vacuum also,
that the engineer may be able to see at a glance the
quantity of steam consumed, and to compare with
it the amount of work done. It is not possible that
the back pressure resisting the motion of the piston
shall be less than the pressure of the atmosphere,
but it may be a great deal more, and very commonly
in non-condensing engines the line of resistance is
as much as 2 or 3 Ibs. above the atmospheric line,
though it is quite possible to avoid this excess
altogether, as is shown in diagrams Nos. 6 and 9.

The mean pressure is ascertained in the manner
already directed for obtaining the pressure in con-
densing engines above the atmospheric line, and
the power is calculated in the same way.

For example, let it be required to find the effec-
tive power exerted by the engine from which
diagram No. 6 was taken, the diameter of the cyl-
inder being 18", the stroke of the piston 42", and
the number of revolutions 60 per minute

BICHAKDS STEAM-ENGINE INDICATOR. 47

The mean pressure of steam during the
stroke, above the resistance of the at-
mosphere, was 25 Ibs,

From this we must subtract the pressure
required to run the engine alone, say. . 1.75 Ibs.

And the increase of pressure required to
overcome the increased friction when
the load is on, estimated at 5 per cent. . 1.25 "

3 Ibs.

Leaving effective pressure 22 "

The area of the piston is 254.5 square inches,

Which, multiplied by the velocity of
the piston 420 feet per minute,

50900
10180

And divided by 33. (000)106(890.0(3. 24
99

129
132

Gives 3.24 horse-powers, for
each pound of pressure on
1 square inch during the

stroke 3.24 horse-powers,

Multiplied by 22 Ibs. pressure,

648
648

Gives 71 . 28 effective horse-powers,

assuming the pressure on the opposite side of the
piston to have been the same.

48 RICHARDS STEAM-ENGINE INDICATOR.

In the same manner, on stationary engines, the
power shown by the frictional diagrams can be
calculated, and by diagrams taken when the shaft-
ing only is being driven, and when greater or lesser
proportions of the whole resistance are being over-
come, and on vessels at different depths of immer-
sion.

Generally, engines will give the same figures at
each revolution, the pencil retracing the same line
so long as the resistance continues the same ; but
sometimes this is not the case, as in the engine
from which the diagram just calculated was taken,
where are shown four distinct expansion curves.
In such cases care must be taken to obtain the
average diagram. Also, in comparing the pressures
required to overcome different resistances, it is es-
sential that the speed of the engine in each case be
the same, a requirement often disregarded.

In all calculations of power from the diagram, it
is assumed, and correctly so, that the value of each
unit of motion of the piston is the same, whether
measured at the extremes or in the middle of the
stroke. The motion of the crank should be uni-
form; and if this is the case, the divisions of the
time occupied in a revolution can be accurately
measured on the circle which it describes. The
motion of the piston, on the contrary, changes at
every point of the stroke. At the instant when the
crank is on the centre it is at rest; then its speed,
at first infinitely slow, becomes gradually acceler^

RICHARDS STEAM-ENGINE INDICATOR. 3

ated, until, at the point where the direction of mo-
tion of the piston and that of the crank-pin coin-
cides, the velocities of the two are equal, and for
some distance before reaching and after passing
this point they differ but little ; then its motion is
gradually retarded, until on the opposite centre it
is at rest again.

TO MEASURE FROM THE DIAGRAM THE AMOUNT
OF STEAM CONSUMED.

For this purpose, draw the line of perfect vacu-
um, if not precisely known, at 14.7 Ibs. below the
atmospheric line. Ascertain how much the clear-
ance and the thoroughfare add to the length of the
cylinder at one end, and add a proportionate quan-
tity to the length of the diagram by a line drawn
perpendicular to the atmospheric line, at the proper
distance from the admission line. Then ascertain
the point in the stroke at which the steam is
released, and the pressure in the cylinder at that
point. Multiply this pressure, reckoned from the
line of perfect vacuum (and which must be taken
before the exhaust-port has been opened), by the
sectional area of the cylinder in square inches, and
the product by the length of the stroke in inches,
up to the point at which the steam was released,
and including the addition for the clearance and
thoroughfare, and divide by 14.7, and the quotient
will be the number of cubic inches of steam, at the

60 RICHARDS' STEAM-ENGINE INDICATOR.

pressure of the atmosphere, discharged from the
cylinder at a single stroke. If the valves do not
leak, and there is no water with the steam, the cubic
contents of the cylinder multiplied by the pressure,
at the point of cut-off, should equal the cubic con-
tents multiplied by the pressure, at the point of
release, and in a compound engine the cubic con-
tents of each cylinder multiplied by the pressure,
at the point of release, should give the same result.
Multiply this by the number of strokes in an hour,
and divide the product by 1728 to reduce the cubic
inches to cubic feet, and the quotient again by 1700,
to reduce the steam at atmospheric pressui a to
water, and the result will be the number of cubic
feet of water used per hour; multiply this by 62.5
for pounds, and divide the product by 8.33 Ibs. for
wine gallons. The supply of water to the boilers
will need to be greater than the quantity thus ascer-
tained, and the excess required will measure the
aggregate loss from all causes, including leakage,
priming, blowing off, and radiation from the cylin-
der and pipes where the water of condensation does
not flow back into the boiler. It is essential, of
course, that the diagram measured shall represent
the uniform power exerted, or the mean power, if
it is subject to variations.

The detection in this manner of losses of heat,

from occult causes, is one of the most remarkable

and important services which have been rendered by

the Indicator. It has been proved in some cases

RICHARDS' STEAM-ENGINE INDICATOR. 51

that nearly or quite twice the volume of steam
must have entered the cylinder at every opening
of the ports, either in the form of steam or of water
already condensed, that existed in the form of
steam at the point of cut-off. The field here pre-
sented is one of the most useful in which the Indi-
cator can be employed.

OBSERVATIONS ON THE SEVERAL LINES OF THE
DIAGRAM.

In order to point out clearly the principal points
of excellence and defect in the action of engines,
which are made known by the Indicator, it will be
best to consider each line of the diagram separately,
beginning at the commencement of the stroke. .

I. THE ADMISSION-LINE.

At low pressures of steam this line may be very
nearly vertical, especially when the opening of the
ports is preceded by considerable compression of
the steam in the cylinder, as in diagram No. 1.
Diagram No. 13, also taken from a celebrated
steamship, shows a more gradual opening, but not
preceded by any compression. At high pressures
it is important to avoid the shock of the full force
of the steam on the centre, especially when there
has been no compression. Diagrams Nos. 6 and 7,
from non-condensing engines, show a moderate
advance of the piston, and, the former especially, a

52 RICHARDS' STEAM-ENGINE INDICATOR.

•

considerable movement of the orank, while the pres-
sure was being attained in the cylinder, the latter
with and the former without precedent compres-
sion. These are all excellent admission-lines.

The direction of this line is determined by the
amount of lead given to the valve, for which no
general rule can be laid down. It depends upon
the speed of the piston, the proportion between the
area of the ports and that of the cylinder, the
rapidity or slowness of the opening movement, and
the density of the steam already in the cylinder at
the instant of opening. The proper lead can be
ascertained only by the application of the Indica-
tor. Without its assistance the best judgement is
liable to err in a case presenting novel conditions.
By the best judgment is meant a judgment formed
by careful comparison of the lead given with the
admission-line drawn by the Indicator, in a wide
diversity of cases.

II. THE STEAM-LINE.

Here we find engines divided into four classes,
namely —

1. Those in which the valves have an invariable
motion, without any or with only very trifling lap,
causing the port to remain open, or, technically,
the steam to follow the piston, quite or nearly to
the envl of the stroke.

lUCHAKDS' STEAM-ENGINE INDICATOR. 53

2. Those in which the valves have also an in-
variable motion, but with more or less lap, causing
the steam to be cufc off at a certain fixed point of
the stroke.

3. Those in which the point of cut-off may be
varied by hand, either by means of the link motion
or of an independent cut-off gear; and,

4. Those in which the point of cut-off is adjusted
by the action of the governor, according to the
changes either in the pressure of steam or the re-
sistance to be overcome.

In the first two classes, when less than the full
pressure is required in the cylinder, the governor
or the engineer adjusts the pressure by changing
the position of the regulating valve. In the third
class the regulating valve may be employed for this
purpose, but the more usual and better way is to
run such engines with this valve entirely open, and
to adjust the mean pressure in the cylinder by
changing the point of cut-off. Engines of the fourth
class have no regulating valve, but the full attain-
able pressure of steam is admitted to the cylinder.

The action of the regulating valve varies the po-
sition of the steam line upward or downward, to
that distance from the atmospheric line which gives
the mean pressure required. The action of the
cut-off gear, on the contrary, varies its length for
the same purpose. In engines in which the steam
follows to the end, or nearly to the end, of the

51 RICHARDS' STEAM-ENGINE INDICATOR.

stroke, and indeed in all cases where the pressure
is reduced between the boiler and cylinder by the
action of the regulating valve, it is a matter of very
little interest what the steam-line may be. Not
only its distance from the atmospheric line, but
also its direction, is changed by every change in
the position of the regulating valve, so that it is
not at all a fit subject for consideration.

In engines which have no regulating valve, or
where it is not employed, as in marine engines ex-
cept in rough weather^ the steam -line should ap-
proach nearly to the line of boiler pressure, and
should be parallel with this line up to the point of
release or cut-off. Diagrams Nos. 1, 6, 8, 9, afford
examples of correct steam-lines, except that in No.
1 it is not continued parallel nearly up to the point
of cut-off. Diagram No. 10 shows a slight fall of
the steam-line as the piston advanced, but the
point of cut-off is well shown. Diagram No. 12
from a marine condensing engine, at 336 feet travel
of piston per minute; and Nos. 2, 3, 4, and 5, from
a locomotive, at 730, 820, and 950 feet travel of pis-
ton per minute, afford, on the contrary, examples
of bad steam-lines. The boiler pressure is very near-
ly attained at the commencement of the stroke, in
the first case, by lead given to the valve, and in
others by lead superadded to excessive compres-
sion ; but as the piston advances, the pressure falls
with great rapidity, and the point at which the
port was closed there is no means of discovering.

RICHARDS' STEAM-ENGINE INDICATOR. 55-

In all these cases the passage of steam to the valve-
chamber was entirely unimpeded. Diagrams Nos^
15 and 16 are good admission and steam lines.
Locomotive -diagrams Nos. 19, 20, and 21, are re-
markably good steam and admission lines. In No.
22, steam-line falls off slightly. The nature of
the steam-line depends principally on the propor-
tion between the area of the ports, supposing them
to be, as they ought, the smallest passages through
which the steam is taken, and the cubical capacity
of cylinder to be filled in a given time. A given
cubical capacity may be formed in the same time-
by the slow advance of the piston in a larger cylin-
der, or by its more rapid advance in a smaller one.
The sectional area of cylinder and the speed of the
piston must be equally considered in determining"
the area of the ports, as they are equal elements irt
determining the capacity of cylinder to be filled.

While, therefore, very high velocity of piston
does not render impossible the attaining of a cor-
rect steam-line, still the size of port required for
this purpose becomes so considerable, and the-
amount of power absorbed in working the valves,
under the pressure which is generally associated
with high speed of piston, is already so serious, that
with the present form of valve in use — on locomo-
tives, for example — it is better probably to submit
to the defect at high velocities, than to attempt to
mend it by enlargement. Improvement in this fea-
ture can be looked for only from a radical change

RICHARDS STEAM-ENGINE INDICATOR.

in the valves and movements. It should be ob-
served, however, that the velocity of piston at
which diagrams Nos. 7 and 8 were drawn was 600
feet per minute. Another cause often contributes
largely to injure the steam-line, especially in con-
densing engines — namely, the condensation of the
steam on entering the cylinder ; and to this the
enormous fall of pressure in diagram No. 11 must
undoubtedly be in part attributed, the smallness
of the ports not being sufficient to account for it.

There is obviously a point beyond which expan-
sion can not be advantageously carried, because it
is possible to cut the steam off so early that even
with the highest pressure the engine will not per-
form any duty at all, but only run itself. Of course
the power absorbed in running the engine should
be only a small percentage of the gross power ex-
erted. But there is also another limitation. The
loss of heat by radiation and conduction, external
and internal, is far greater than was till lately gen-
erally supposed. It is possible to protect pretty
thoroughly against external radiation ; but against
internal radiation, which is so much greater than
the other, as the capacity for heat of the exhaust
steam, at the density it may have, is greater than
that of the atmosphere, it is not possible to protect
at all, and the earlier the steam is cut off, the
greater is the proportionate time during which the
exposed surfaces are being cooled, and the smaller
the quantity of steam admitted from which they

RICHARDS' STEAM-ENGINE INDICATOR. 57

must be warmed again.* The phenomenon of a
higher terminal pressure, in cylinders working
steam expansively, than the law of the gases could
account for, was generally explained, until quite re-
cently, by supposing that the valves leaked ; but
when it was found to be universal, and to be most
remarkable where the steam was most charged
with moisture, thoughtful men were not long in de-
tecting the true cause. The temperature of this
moisture, as it enters the cylinder, is the same as
that of the steam, and being in great part relieved
from pressure by the expansion, it will instantly
assume the gaseous form, provided the heat, which
must be rendered latent on its change of state, is
furnished. This is abstracted from the surfaces
with which the particles of moisture come in con-
tact, and the excess of terminal pressure above
that which should exist measures the heat thus
lost, and which must be regained at the commence-
ment of the next stroke from the entering steam.
If the steam enters the cylinder nearly dry, this
process, when the cylinder becomes heated, soon
reaches a very moderate point, as is illustrated in
diagram No. 6, where the theoretical curve is closely
approximated to. Diagrams No. 7 and 8, on the

* The recent experiments of Professor Tyndall reveal the-
astounding fact, that the power of aqueous vapor, at the
pressure of the atmosphere, to absorb heat, is 6,000 timea
greater than that of dry air.

58 RICHARDS* STEAM-ENGINE INDICATOR.

•contrary, being taken at the Great Exhibition of
1862, where the steam was charged with moisture
In an excessive degree, show a great amount of
re-evaporation to have taken place, as the pressure
fell in the cylinder.

The best means at present known for diminish-
ing the loss from this cause is, to dry the steam by
moderate superheating, perhaps sufficient to affect
-the thermometer but very slightly, since every atom
of moisture must change its state to steam before
ihe temperature can rise above that due to the
pressure. The height of the terminal pressure, as
^shown by the Indicator, above that which the law
•of Mariotte and the law of contraction of gases by
-cooling call for, affords some indication of the loss
from this cause. If the curve drawn could agree
with the requirements of these laws, there would
&e demonstrably no loss at all ; but this is not at-
tainable. Indeed, the higher temperature of the
.cylinder would probably affect sensibly the fall of
pressure, even if the steam was perfectly anhydrous.
It is obvious, that the percentage of loss will be
•diminished, other circumstances being the same, in
proportion as the speed of piston is increased, the
actual loss continuing the same, but the power ex-
erted becoming greater. Whether the employment
of two cylinders enables this loss to be avoided to
a greater extent than it can be in a single cylinder,
must at present be regarded as an open question,
3*

RICHARDS STEAM-ENGINE INDICATOR. 59

and is one the discussion of which is foreign to the
purpose of this work.

To expand steara properly, it is essential that it
be cut off instantaneously — that is, that the port
shall be closed so quickly, that the pressure shall
not fall in the cylinder, from the advance of the
piston during the operation of closing. This Indi-
cator enables us to pronounce unerringly upon the
value of every means which is employed to effect
this object.

Diagram No. 6 shows unquestionably the closest
approximation to this requirement. It was taken
from an engine in the city of New York, of the cel-
ebrated style known as the Corliss Engine, which
is extensively used in the eastern part of the Uni-
ted States for stationary purposes. The speed of
piston of this engine was 420 feet per minute.

Diagrams 9 and 13 show the cut-off made by the
Sickels valve-gear, also in extensive use in the
United States, especially on boats and vessels. No»
9 was taken from a non-condensing stationary en-
gine, making 30 revolutions per minute, and No.
13 from the engines of a steamship at 16 revolu-
tions per minute. It is hardly necessary to add
that these were not taken with the Eichards Indi-
cator. The theoretical expansion curves cannot
be drawn on either of these diagrams, because the-
amount of waste room, which is considerable, from
the nature of the valves employed, is not known.

<<50 RICHARDS STEAM-ENGINE INDICATOR.

The speed of piston in each was about 300 feet per
minute.

Diagrams Nos. 7 and 8 were taken from the Al-
len Engine at the Great Exhibition of 1862, at a
rspeed of piston of 600 feet per minute. The pres-
sure fell somewhat at this great speed, as the clos-
ing movement of the valve was being completed,
-giving a rounded corner. In Diagram No. 7 we
iind the expansion curve changed to a waving line.
The pressure of steam was removed from the pis-
^on of the Indicator with such extreme suddenness
•that the reaction of the spring was necessarily vio-
lent; but the rounded, flowing nature of the oscil-
lations show the action of the instrument to have
"been frictionless, and these gradually subside into
~the correct curve, which the mean of the oscillations
gives throughout, as shown. Diagram No. 10,
-from the engines of a steamship, shows very su-
perior action of the cut-off gear.

The vice which is the opposite of this excel-
lence is technically termed wiredrawing, and con-
sists in a gradual fall of pressure in the cylinder,
"while the port is being closed. It is illustrated in
-various degrees in several of these diagrams, and is
41 source of serious loss. The object of cutting off
is, to obtain the greatest mean pressure with the
lowest terminal pressure, and it is clear that the
sharper the cut-off the more completely this object
is attained. For example, in diagram No. 1, the
•fiteam expands to a pressure of 17 Ibs. at the point

RICHARDS' STEAM-ENGINE INDICATOR. 61

of release, and a mean pressure of 21.28 Ibs. is
exerted during the stroke ; had it been cut off
sharply at the point c, it would have expanded to a
pressure of 9 Ibs. at the point of release, describing
the curve c g, and would have exerted a mean pres-
sure of 15.87 Ibs. But 21.28 : 15.87 : : 17 : 12.67.
The gain of steam from cutting off sharply would
be then 12.67 - 9=3.67 Ibs., or 29 per cent. But
this is by no means the full amount of the gain, for
so much less steam being to condense, 1 Ib. better
vacuum at least would have been formed, and the
boilers would easily have maintained a pressure 5
Ibs. higher, with much more moderated firing ; so
that the full mean pressure of 21.28 Ibs. would have
been obtained by cutting off at the point c, and
expanding to a terminal pressure of 10.5 Ibs., a gain
of §J5 Ibs., or 38 per cent., and improvements equal
to this have by this single means been often real-
ized in practice. The slide-valve in its best form
wiredraws the steam considerably, unless a great
travel is given to it; the vicious practice of making
the end V-shaped of course raises the loss from this
cause to the very highest point.

Diagram No. 14 shows the action of a single
slide-valve with a serrated end, expressly contrived
to wiredraw the steam as much more than it can be
with the ordinary slide as possible.

The mean pressure for different points of cut-ofij
may be found by

62 RICHARDS' STEAM-ENGINE INDICATOR.

HYPERBOLICAL LOGARITHMS.

RULE. — Divide the length of the stroke by the
length of the space into which the steam is admit-
ted; find in Table No. IV. the logarithm of the
number nearest to the quotient, to which add 1, the
sum is the ratio of the gain; then find the terminal
pressure, by dividing the initial pressure by the
proportion of the stroke during which the steam is
admitted, and multiply it by the logarithm -J- 1,
found as above; the product will be the mean pres-
sure through the stroke.

EXAMPLE. — Suppose the length of the stroke to
be 48 inches, the initial pressure to be 40 Ibs. per
square inch, and the steam to be cut off at 12 inches
of the stroke, what will be the mean pressure ?

48^12=4. Hyp. log. of 4=1.38629+1=2.38629.

Then, 40 -^ 4 = 10 X 2.38629 = 23.8629 Ibs., the
mean pressure required.

To find the initial pressure, add the atmospheric
pressure, 15 Ibs., to the pressure shown by the gauge,
and from the mean pressure found as above sub-
tract the counter-pressure, to ascertain the actual
mean pressure exerted. Thus, in the above case,
the gauge is supposed to show a pressure of 25 Ibs.
only, and if the calculation is being made for a con-
densing engine, the estimated loss from imperfect
vacuum must be subtracted, and if for a non-con-
densing engine, the pressure of the atmosphere,
and also any estimated counter-pressure above that,

must be subtracted from 23.8629, the mean pressure
found by the calculation.

The editor remarks that the above rule requires
a little qualification, to be considered correct. If
the diagram shows the cut-off at J of the stroke, it
does not follow that | is the grade of expansion, be-
cause the clearance has not been taken into account.

EXAMPLE. — Suppose the length of the stroke to
be 36"; initial pressure, to be 50 Ibs. per square
inch, and the steam to be cut off at 9" of the stroke,
what will be the average pressure ?

36-^-9=4. Hyp. Log. of 4=1.38629+1=2.38629.
Then 50-1-4=12.5X2.38=29.75, mean pressure
required. This is correct without taking the clear-
ance into account.

Now, let us see what the result is, when we add
the clearance in the following examples; which is
an actual case occuring in my practice during the
week in which this was written.

Engine 36" strokeXl^" diameter, cutting off at J
(9") ; initial pressure 50 Ibs. to the square inch ;
revolutions per minute, 80 ; clearance equal to -fa
of the cubical contents of the part of the cylinder
occupied by the piston stroke ; or what is the same
thing, -fa of the stroke, which is equal to 1.64",
added to 9", the point of cut-off, is 10.64" ; which
being divided by the length of the stroke, gives us
as a quotient 3.39, with a mean pressure of 32.59
Us., as calculated by the above rule, adding the
clearance.

64 RICHARDS* STEAM-ENGINE INDICATOR.

Computing it by the same rule, without taking
account of the clearance, the average pressure is
29.75 Ibs. The result stands thus, computing with

the clearance added 73.00 H. P.

Without the clearance 66.64 " "

Difference 6.36

In using Table No. V., the clearance must be
added to get the correct mean pressure.

IV. THE EXHAUST LINE AND THE LINE OF COUNTER-

may properly be considered together. It is, of
course, desirable that the pressure of the steam be
got rid of as completely as possible before the
piston commences its return stroke. This is
accomplished in a non-condensing engine by having
the exhaust port and passages sufficiently large, and
opening the port a sufficient time before the termi-
nation of the stroke, according to the density of the
steam to be released and the velocity of the piston.
The passages and pipes communicating with the
atmosphere should be at least 50 per cent, larger
than the ports, and as free from angles as possible.

These requirements apply to condensing engines
even more strongly, and in addition the condenser
and air-pump must be able to maintain a proper
' vacuum.

Diagrams Nos. 6 and 9 show no back-pressure at

RICHARDS' STEAM-ENGINE INDICATOR. 65

all above the atmosphere ; diagrams Nos. 7 and 8
show a trifling back-pressure, attributable to the
number of angles in the pipe necessary for connect-
ing with the exhaust main at the Exhibition.

Diagram No. 10 exhibits remarkable exhaust and
counter-pressure lines, obtained by a surface con-
denser, while No. 13 shows a great loss of power
from imperfect vacuum, which was very partial at
the best, and that only gradually obtained.

V. THE COMPRESSION-LINE.

This line, when it exists, is formed by the closing
of the exhaust port at some point before the termi-
nation of the stroke, when the advancing piston
compresses the confined steam to a density propor-
tioned to the decrease of volume. This is illustrated
in various degrees in several of the diagrams here
shown. This action occasions a loss of power, but
not much waste of stream, because the confined
steam reacts on the return stroke with a force equal
to that expended to compress it. It is useful on
engines running at high velocities, by taking up
gradually all looseness of the joints, and prevent-
ing the entire force of the steam from striking
suddenly on the piston. Indeed, so important is
the compression in preventing shocks on the centres
in engines of this class, that probably locomotives
could not be safely run without it. At the same
time, the nature of the valve and gear employed on

66 BICHAKDS* STEAM-ENGINE INDICATOR.

this class of engines is such, that when cutting off
very early the compression becomes excessive,
involving an increase in the counter-pressure as
the piston approaches the centre, which is quite
unnecessary for any useful purpose, as is illustrated
especially in diagram No. 4. At any ordinary
number of revolutions per minute made by station-
ary or marine engines, the compression is not
required, but in a moderate degree is never,
perhaps, objectional.*

* We do not think our author gives sufficient prominence
to the advantages of compression ; all engines require it, to a
greater or less degree, depending, of course, on the speed and
action of the valves. Our practice is, when we can control
the exhaust valves, to compress from one-half to the whole
initial pressure. A great point gained by compression is, to
take up and store away, to assist on the return stroke the
momentum of the piston and its connections with the crank ;
also, to fill the ports, passage-ways and clearance with exhaust
steam, that we may not have to call on the boiler for it. It is
certainly easier on the machine to take up slack motion of the
joints thus gradually, than to take high steam on before
reaching the centre. It is true, we reduce the capacity of the
cylinder, but lose no steam ; on the contrary, save the momen-
tum of the reciprocating parts, by compressing a portion of
the exhaust steam. When the slide-valve is used, it serves
to partially balance it during the compression, thereby reliev-
ing it from friction and wear ; a very important consideration,
particularly on large valves. We prefer also to give very little
or no steam lead; let the centre be past or nearly so, and the
piston on its way back, before the steam is admitted.

Many a crank and its connections have been broken, brasses

RICHARDS' STEAM-ENGINE INDICATOR. C7

Diagram No. 12, not taken by the Richards Indi-.
cator, shows the usual form of diagram made by the
double opening slide-valves now in general use on
marine engines, with an independent cut-off valve.
It will be observed, that the steam line is well main-
tained until the cut-off valve commences to close,
when the pressure falls in an increasing ratio, prob-
ably to about the pressure indicated by the dots at
the exact distance of closing.

In the preparation of this paper, and in the
selection of diagrams for its illustration, its object
has been carefully kept in view, and while it is
hoped that nothing has been omitted which is
essential to guide one before unacquainted with the
Indicator in learning how to employ it correctly
and intelligently, care has been taken to introduce
only those topics, and to consider these, only to
that extent which seemed to be necessary for this
purpose.

THE THEOEETIC CURVE AND ITS USES.

When we wish to know the condition of the
internal working of an engine from a diagram we
have taken from it, we make a perfect diagram

worn out; heating, straining, and thnmping, with all their
concomitant evils, are daily caused by excessive steam lead ;
while, by compressing, the piston meets the thin elastic vapor
remaining in the cylinder without a shock. It is technically
called " cushioning," a most appropriate term.

68 BICHARDS STEAM-ENGINE INDICATOR.

around it so we may compare the one with the
other.

To do this : First, we ascertain the clearance
between the piston and cover, also the areas of the
ports and passage-ways clear back to the valves,
both steam and exhaust, if they be separate.

This we reduce to cubic inches ; we then get the
cubic inches of the cylinder, or that part of it occu-
pied by the stroke. Suppose the cylinder to be 14"
diameter, and 36" stroke, it will contain 5541.48
cubic inches. Now, then, suppose our clearance is
206.44 cubic inches ; this being divided into the
contents of the stroke part of the cylinder, 5541.48,
gives us 27, or is ^ part of it. We then add to the
steam end of our diagram ^ part of its length.
We then draw the line of perfect vacuum, whether
it is a condensing engine or not. Then we space
the whole in ten or more equal divisions, and erect
lines (ordinates) on these spaces at right angles to
our vacuum line, as shown in diagram No. 0.

We will suppose we have 100 Ibs. from A to B,
Diagram No. 0, measuring from the line A E, and
we cut off at 0, which is ^ or ^; by the law of expan-
sion we should find (having expanded the steam £)
the terminal pressure to be -J- of the pressure at C,
the steam having expanded, $ of the whole diagram.
To find the point where the true curve should bisect
the ordinates, we have numbered them from one to
ten. We find the steam is cut off at 2, the next
ordinate is 3, this being | the length of 2 ; hence,

KICHAKDS' STEAM-ENGINE INDICATOR. 69

we use 2 for the numerator and 3 for the denom-
inator, and so on to the end, using for the numera-
tor the number of the ordinate where the steam is
cut off, and for a denominator the number of the
ordinate whose length we seek.

It often happens in spacing our diagrams that
we can't find a space that will come right in both
divisions of the diagram. In that case we space
the parts from B to C into equal spaces, say from
J" to |" each and then space the remainder the same;
if it should run over the termination of the diagram
it is of no importance, as after the curve is estab-
lished the measure will be taken at the terminal
point. The practical application of the theoretic
curve is this : If we find it below the curve given
by the instrument, we seek for the cause ; if the
engine cuts off short, say at J or less of the stroke,
we may expect to find it a little, say a pound or
two, above, at the last \ or f of the stroke; this is
accounted for by re-evaporation of the water con-
densed in the first part of the stroke. But, if it
should run as it often does 10 or 15 pounds above,
we conclude at once that the steam valve leaks.
If we find the curve made by the instrument fall-
ing below the theoretic line, we are certain that
either the piston or exhaust valve leaks, or may be
both.

Diagram No. 15 was taken from an engine
24" X 48", making 50 revolutions per minute. The
steam valves are of the class known as balanced

70 RICHARDS' STEAM-ENGINE INDICATOR.

poppet ; the exhaust valves plain slide ; point, of
cut-off adjusted by the action of the governor.
Boiler pressure 48 Ibs., steam pipe 6" diameter by
150' in length, the exhaust pipe 1" diameter by 175'
long, scale of the instrument 30 Ibs. to the inch;
work being done, driving two trains of rolls, one
of 20", the other of 16" diameter, with the concom-
itant and other machinery.

It will be observed that the pressure in the cylin-
der fell off some . 10 Ibs. from the initial in the
boiler, which is easily accounted for by the great
length of the steam pipe. The 2 Ibs. back pressure
may be accounted for by the excessive length of the
exhaust pipe ; these defects are no fault of the
engine.

The card is a very excellent one; we rarely see its
equal — no superiors, unless from an engine whose
cylinder is jacketed with high steam. It will be
seen that the lines given by the instrument vary
but little from theoretic curve. The engine was
constructed by Messrs. Woodruff & Beach, under
Mr. Wm. Wright's patent.

Diagram No. 16 was taken from the top of the
cylinder of the steamer Newport; it will be recog-
nized by the engineer as very good. The steam
pressure on the boiler was by the gauge 22 Ibs.,
vacuum per gauge 26". It will be seen that the
diagram shows 20.5 Ibs. The terminal point is sup-
posed to be as should be; yet, not having the data
to calculate the area of the clearance, passage-ways,

RICHARDS' STEAM-ENGINE INDICATOR. 7^

etc., we cannot ascertain where the terminal point
should be, exactly.

If the exhaust had opened a little earlier, it
would have improved the vacuum at its commence-
ment.

Diagram No. 17 is from an engine 24" diameter
X48" stroke, 60 revolutions per minute, Babcock
& Wilcox patent ; cylinder jacketed with steam
from the boiler. The clearance is ^ of the stroke,
boiler pressure 72 Ibs. to square inch, scale 40"=1".

This engine is in the flouring mills of Messrs.
Chapin, Miles & Co., Milwaukie.

The work being done when the diagrams were
taken was driving 4 runs of 4' 6" stones, and 2 runs
of 4' ; 180 revolutions per minute, with all the
required flouring machinery as used in such mills.

We give this data, that any one who wishes can
make the theoretical curve; it will be found almost
perfect.

The expansion line, it will be noticed, is some-
what waved, which is incident to the high speed,
high pressure, and early opening of the valves.

The terminal point of the expansion line will
be found about 3 Ibs. above the true line, caused
by evaporation of water that went over with the
steam.

Another and unusual point is the very near
approach of the pressure in the cylinder to that in
the boiler, being but 2J Ibs. less. When we take
into consideration the speed of the piston, 480' per

72 RICHARDS' STEAM-ENGINE INDICATOR.

minute, the result is extraordinary and seldom
attained.

Diagram No. 18 ; these cards were taken from
a Wilcox air engine, and beautifully illustrate the
delicate action of the Richards Indicator. Fig. 1
is from the working cylinder ; the receiving line
shows the induction valve to be slightly behind
time; the pressure gradually reduces the first of the
stroke, as the reservoir containing the compressed
air is small, but as soon as the pump begins to
deliver into the reservoir, the pressure continues
uniform till the induction valve closes near the end
of the stroke; the exhaust is free, and there is a
slight compression at the end of the return stroke.

Fig. 2 is from the pump, whicb is § of the capa-
city of the working cylinder, and shows the gradual
increase of pressure as the piston descends and
compresses the air; the curves or waves at the
point of greater pressure show the power required
to open the eduction valve; the pressure then con-
tinues uniform till the induction to the working
cylinder closes, when the pressure runs up ; at the
commencement of the return stroke of the pump
piston, the pencil mark inclines back, showing the
time required for the closing of the eduction valve,
and the wave below the atmospheric shows the
time and power for opening the induction valve.

The working cylinder is 16" X 16" stroke, and
makes 70 revolutions per minute, scale 12 Ibs. to
one inch.

RICHARDS' STEAM-ENGINE INDICATOR. 73

The pump, Fig. 2, is § the capacity of the work-
ing cylinder, Fig. 1; hence, we measure the average
pressure of the two diagrams, each separately.
Suppose the working cylinder to show an average
of 10 Ibs. to the square inch, and the pump diagram
to show 9 Ibs. to the square inch. The pump being
f of the capacity of the working cylinder, we divide
the mean pressure, which we have assumed as 9 Ibs.,
by 3, the quotient is 3, this added to 10 is 13; 3 sub-
tracted from 9 leaves 6, which subtracted from 13
leaves 7 Ibs. effective pressure per square inch on
the piston.

Our author concludes the work with a graphic
account of " A Bide on the Buffer Beam" on the
Great Eastern Railway, making the trip from Lon-
don to Yarmouth (England) in company with Mr.
Zerah Colburn, for the purpose of taking diagrams
from the engines, in which they were eminently
successful; which the compiler of this, owing to the
prescribed limits of this work, reluctantly feels
compelled to omit, and substitute an account of a
similar, though shorter, trip — from Wilmington,
Del., to Philadelphia, on the Philadelphia, "Wil-
mington and Baltimore E. E. Through the kind-
ness of Mr. G. W. Perry, master of machinery of
that road, Locomotive No. 50, a first-class express
engine built by " the Taunton Locomotive WTorks"
— cylinders 16" diameter by 24" stroke, four driving
wheels 5' 6" diameter, making 305.46 revolutions to
fche mile — was placed at the disposal of the writer,

74 RICHARDS' STEAM-ENGINE INDICATOR.

and fitted for the occasion under his directions by
Mr. S. A. Hodgman, the able and efficient master
mechanic of the shops. The engine is outside con-
nected. The diagrams were taken from the for-
ward end of each cylinder. — Short J ' ' pipes were
screwed into the top parts of the cylinder covers,
with elbows f " internal diameter pointing upwards,
to which the Indicators were attached. An iron
rail was secured to the signal flag-stands on the
narrow platform in front; a packing-box some 9"
high served as a seat for each operator, with his
back to the wind, and the Indicator between his
knees.

The method employed for giving motion to the
papers was very simple. A plank on each side of
the boiler, running from the cab to the platform,
about 3 ' above the cross-head, and directly over it,
which was used for the purpose of going forward
to oil, etc., was morticed through in the proper
place, and a bracket with a hole through it to
secure the arm to, was bolted to the plank beside
the mortice. A stud with a nut on it was fastened
to the bracket, pointing outwards horizontally. A
light arm swung from this stud and received a
vibratory motion from another stud screwed into
the side of the cross-head, working in a well-fitted
slot in the lower end of the arm. A button-headed
pin was inserted in this arm at about 7" below the
point of suspension, and to this was attached the
cord leading directly to the Indicator, giving to the
3

RICHARDS' STEAM-ENGINE INDCCATOR. 75

paper a motion of 4J". Great care was taken to
set the arm, so that when the engine was on the
half-stroke and the cord attached to the instru-
ment, it might be at right angles with the arm.
The cord had a hook about 2" long, with a bend
about 1J" diameter, with a corresponding one on
the instrument cord, which made it easy to attach
under any speed. The hook on the cord was
secured by two other cords to keep it in position,
allowing it to move back and forth, but not to fall
when disengaged, where it could not be readily
seized.

It was arranged with the engineer that he should
run at all times with the throttle-valve fully open,
governing the speed entirely by changing the point
of cut-off. Everything being ready, Mr. Hodgman,
the master mechanic of the shops, and myself, pre-
pared to mount the platform. It being the month
of November, and not being very warm, an extra
overcoat was put on; a pair of woollen gloves,
fingers amputated at the second joint, leaving
enough of the finger bare to manipulate the instru-
ments, were found to work well.

Our first essay was with the engine and tender
alone, to see that all was right. We took several
diagrams, both on the forward and backward mo-
tions. We found the valves remarkably well set.

Diagram No. 19 is one of a pair that were taken
when running about 20 miles per hour; working
the steam full stroke, both backwards and forwards,

76 BICHAKDS* STEAM-ENGINE INDICATOR.

shows how nearly the two actions correspond. Its
mate from the right-hand cylinder is a perfect fac-
simile of the one we engrave. In taking these cards,
the throttle was quite open. Pressure of steam not
noted. The scale of the instrument 40 to the inch.
During these preliminary experiments, an unfortu-
nate accident happened to one of the instruments
by breaking a spring. Not having an extra 40
spring, we substituted a 30 spring in each instru-
ment, and that we might get sufficient range, we
put washers between the end of the spring and the
piston, of sufficient thickness to carry the piston
down to the vacuum line, thereby giving us a scope
of 15 Ibs. more, and sufficient to answer the require-
ments for 105 Ibs. pressure in the cylinders. I men-
tion this for the reason that should the young
engineer meet with a similar mishap, he may be
posted on the subject. The delay caused by this
mishap prevented us from carrying out a programme
we had made previously. At 4 p. M. the express
train arrived from Baltimore, which it had been
arranged for us to take to Philadelphia. We took
diagrams at speeds varying from 30 to 60 or more
miles per hour, with great facility, at full stroke, and
cutting off at various points. In consequence of
our weak springs, our experiments were limited in
pressure to 105 Ibs., hence we could not maintain
our speed when cutting off short.

Diagram No. 20, scale 30 to the inch from the
right hand cylinder, cutting off at about one fourth

EICHAEDS

^-'1 -:R"

STEAM-ENGINE INDICATOK.

stroke, was taken at 60 miles per hour, piston making
1,222 feet per minute, 305.46 revolutions. Notwith-
standing this extraordinary speed of piston, the
lines are all well denned, showing distinctly the
points of cut-off and release. A remarkable point
in the diagram is, that though the pencil passed
over it certainly twice or more, the lines are
very near to each other, showing that even under
this unprecedented speed of piston the instrument
was uniform and reliable in its action. This is not
a selected diagram ; all others taken on the trip
show the same characteristics,

Diagram No. 21, same scale, from the left-hand
cylinder, cutting off one notch shorter, with a higher
pressure of steam, taken next after the foregoing,
exhibits the same general features, though taken
under a higher speed.

Diagram No. 22, same scale, was next taken,
working full stroke, with, as will be seen, throttle
full open ; the speed increasing to such a degree
that the engineer thought it prudent to put on £
cut-off.

This, as do all the other diagrams taken from the
engine, shows most marked points in the construc-
tion and setting of the valves; notwithstanding the
great speed, the steam line is held uniform to the
points of release. The exhaust line is all that can
be desired. The back pressure is merely nominal,
the exhaust nozzles being 4 J" each. In getting the
diagrams, the writer was ably seconded by Mr.

78 RICHARDS' STEAM-ENGINE INDICATOR.

Hodgman, who, though it was his first attempt at
taking diagrams, was remarkably efficient and cor-
rect.

We have spoken of the accuracy of the valve-
setting. These valves were set wholly by marks
on the wheels, slides, and valve-rods, with steam
on, and of course valve-chest covered, which is the
only method by which they can be correctly set,
owing to the expansion of the parts by heat.

We would here refer the engineer who wishes to
be well informed on the important art of valve-
setting, to a very excellent work on the slide valve
and link motion by Mr. W. S. Auchincloss, recently
published by D. Van Nostrand, 23 Murray-street,
New York, which is the result of great research and
practical experience; from which we copy:

"HOW TO SET A SLIDE VALVE HAVING EQUALIZED
EXHAUST.

" 1. Place the crank at the 180° location, mark
on the cross-head and one of its guides opposing
' centre punch ' points,

" 2. Bring the crank to the zero and mark a se-
cond point on the guide. The two points thus
found, measure the length of the stroke. Move the
eccentric until the valve has the required lead for
the forward stroke.

" 3. Advance the crank in the direction of the
motion until the exhaust of the opposite stroke

RICHARDS' STEAM-ENGINE INDICATOR. 79

closes ; scribe a line across the guide which shall
pass through the point on the cross-head.

" 4. Move the crank until the other exhaust closes
and scribe a second line on the guide.

" 5. If now the exhaust should close at equal dis-
tances from the commencement of each stroke, the
motion would be in adjustment; if not, alter the
length of the eccentric rod until the closure becomes
equalized, then return the crank to the zero posi-
tion, and alter the angular advance of the eccentric
until the required lead of the forward stroke is
secured.

" The position of the valve at the moment of
closure may readily be fixed by means of a ' valve
gauge ' fitting centre punch points on the valve
stem and its stuffing box.

" The above process will serve also to equalize
the cut-off if the valve be proportioned for this
object."

The trip was not without its discomforts, however
successful it might have been, being accomplished
on a November afternoon, with rather a low ther-
mometer ; with nothing at our backs to break off
the wind, with low seats and otherwise constrained
positions, we at the conclusion of our trip found
ourselves somewhat cold and a little stiff. Had it
been a summer day, this source of discomfort would
not have been, and we should have enjoyed the
excitement of our trip much.

So far as it is known to the writer, the above is

80 RICHARDS' STEAM-ENGINE INDICATOR.

the first successful application of the Indicator to
a locomotive, when making a regular trip on the
road, in this country. It is quite certain that there
is no Indicator known but the Richards, that can
be successfully used for the purpose. We will con-
clude with Mr. Porter's concluding paragraphs of
his " Bide on a Buffer-Beam :"

" These diagrams are taken under fewer difficul-
ties than would be at first imagined, if the weather
is pleasant, and the proper provision is made for
the comfort and security of the operators. The
principal difficulty is from the wind, which, at very
high speed, approaches more nearly to a hurricane
than anything that one is able to experience in this
latitude in any other way, and the labor of resist-
ing it becomes quite wearisome, if the operator is
not somewhat protected from its force. No un-
pleasant sensation whatever is produced by the
rapid motion, the passing of trains is scarcely ob-
served, and if no accident happens, there is no
danger more than in the carriages. Good weather
is essential to the satisfactory accomplishment of
the objects of such an excursion."

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•«*• *-i OO vO rj- >-• ONOO
i\o t^ t^OO ON O O "-•

'-' vr>i/->ON

_ _ ...O "-" covO <H t-^

vo C4 ONVO CO Ot^LOcO"-" ONr^-vorJ-M

CO ^ Tj- uo\O t^. t^OO ON O O <-• N CO •<*•

HHWWWM M IH l-l l-l M NNMWM

vo *s"

•-I O ON(

vovO vO

« W N N M

o OO vO >-o tr>
xOi-iOOiON
r«-> Tf rt xovO

^-oo N O
vO^l-rO'-'
»-'Mroi<4

r-^vo t^ o '4'
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Ln iOvO t^OO

^•vO ^" O co co O ^J" to ^" ON ^< *^ OO M

1-1 ON co cooo ONVO OO <O O ON vovO IN vo

vo « oVoo 06 6 4- o\vd to -4-vo oV 4- 6

•*J- »M t^ -<^- >-, ONVO CO •-< ON t>.vocOvN w

co ^" Tt* vovO vo t^»CO ON ON O *"* N co ^"

OO t^OO •-"
ONOO r^ r-»v
Tj- vovO r^

wi-i rot^«WOOr^
^ "-* OO«J->roOOO vO-^-
t^.OO ON ON O •-*

OO>-<tni-i

COOO u">Tj-rfvOCNTj-i-iONOOOMf^rO

>Tj-rf
coO

LOVO

O vr>\o 10 >-i CO CO O
t^OON-^-io >-ifO'-'

N'-'OO «

ONMt^CO
VO •^•'-" ON
vO t^OO OO

t^» co "-• O •"" Tt-OO rt-
- t^ voco« ONOO
ON O •"• <M C« co

"^ -<t- O co co O Tf-vO -^O "-"NOO
NTJ-C^LOT}- ONONiOt^^OOOt>»>-i

O '-

ONVO

RICHARDS STEAM-ENGINE INDICATOR.

U.UIBIQ

OO O 10 IH OO r^OO

ONVD ON t^ 1-1

IH £.00 1000 viT O O

* oVvd 10

ONO IH

VO N •*
« ^- cT

ONNVO N
CS VO t^ O
t^.00 ON HH
'^-TJ-TJ-IO

vovo
N^»r>

MONCO COOO ON

Rt^VO t^ ON
vo vo vo vo
ON O i-< N co
N COCOCOCO

coOO »0 co co voOO N ONVO

i>- t^oo ON o w N -^t- Br»tsi

^J" tovo r^o\ OI^MCOT!-

COCOCOCOCO •^•Tj-Tj-Tj-^-

VO t

o\ IH
to r^oo

U4UIBIQ

vovo COOO ONOO
w ON CO N t^OO

CM cococo

Nt^^J-NN COVO M

VO vo t^OO ON O IH

TJ-IOVO i>-00 0 IH

cococococo

OO^OIHCIIH t^OOt^.iH COIHVO ONOO 10 ON O
CM COO M 0 CO COOO 00 10 l>.ioOO r<N COONN

LO "*• ^ ^ ^t- 10 u-jvo r^OO
ON O I-" M CO -^ iO\O t^OO
r» cocococo cococococo

IOONIOCO NM 100 *d-

O >-> co 10 l>. ON IH covo
ro Tf iovO OO ON O
Ti-io

vO OO t^ co^O vO TJ-OO ONOO covO vOCMvO r^ioOcoCM
voioO IH r^ ON r>- O ON^- LO >-< coin ^- cooO ON 10 1-^

IH 00 t^> t^OO IH VO CO O O IH
^- rf IOVO t^ 00

T*- iovO r^oo ON

rj- t^.vO O IH

CM OO t^ t^OO iHVOCMOON OCMVOCMONOOOOO'^-ON

COCMCMCMCM COCOTj-iOio K.OO ON " ^ ^-vO ON « CO

O\ O IH CM CO rj- iovO t^OO ON O IH CO ^ iovO «>• ON O

WCOCOCOCO COCOCO OCO CO ^1- ^ ^ ^ rj- rj- r^- -5J- 10

t^OO VO
rj-VO COVO "">

•H CM co •«*• 10

VO t^OO ONO iHCM
vOOvovot>i t^t^

RICHARDS STEAM-ENGINE INDICATOR.

•j^ureja

OOOOOOOQOQ OQOQOOOOON ON ON ON ON ON ON ON ON ON. O

vo ON ON t^ H< mc40Oi-ii-«OOttmoir^ON ONVO ON O
i-iioxoi-imOmi-'vOvO 1-1 m O COM xovoi-i 0* O

r» ON moo vo m m •^•I^NOOV

ON N VO ON COVO O rJ-OO m t^ N t^ N t^ N OO m
'

i-^oo >-< vo 1-1 oo

ON r^ N rj- m ON N N ON Tfr- vo m ON N •-" 00

mmiOOOmOOO

ON N vo N
im-ivOW

ro iov0 00

10 t>.vO COVO VO COOO

ONOO TfvO
COO fO^

N 1-1 N Tj-OO mOONON'-"

rj- t^ O fOvO Orl-t^.i-ivO

CJ CO LOVO t^ ON O « CO ^

lO 10 10 10 10 i-O\O vOVO^O

i-(T}-Tl-i-i

fOOO ONVO

ONVO CO vO O

ONOO ON i-« ^ O VO ^O «-O«O ON
N u-)00 NvnONClVOOTt-OO
W co ^vO t^» OO O M co -^ v~)

^OOOOO ONMir^i-i

C» t^ M OO m ON

O >-< co ^f vO t^

t^.t^ r^r^t^t^.

10 »o 10 10 10

rom covo O
'-'O i-ivoc^

O -i CO -^-VO

M f>. ONOO ^J- r-OO 10 ON •-•
OvOCOvO

>O 10 >O vovO vo

»OOO OO

NVO O ON

MXO>-IOOOO odo-^ovo

VOQiOONTh CMOOvO'-'
10 t^OO ON « W ^l-vo t^. ON

lO rj- O CO Tf 1-1 vo
M t^OO 'sJ-vO

vO M tou-5MvOt^.ioOfONON
I-H OJ OO O OO 1-1 O *OVO N ^ H<

>-< Tf 00 N VO
>t^OO ONt-i M

10 10 iovo vo

rh ON COOO CO OO COOO Tj- O
1OVO OOON"-" NTj-iOt^ON

vovovOvo r>- t^t^t^t^.t>.

o6vdv6o6i-H

t^- O COVO O

to to *-i co »-< ^- cooo oo -r
civdrl o\oo oo O rooo to

COt^r4vO'-'VONt^MOO
voO OO ON >-i N 'T

t*+ ONVO ONOO COCOONMOO

vomm^J'fs» N oo to to vo

VO ON M voOO N vo ON co t^
•-i N -rf- vovO OO ON O M m
»O to to to vo vo vovO VO VO

oo M r^ rj- co co vooo m ON

HH vO O to O vo O vo H« vO

VOVO OO ON I-H C^ rj- vo f>»00

vo vo vo vo t^ t^ t^^ c**- r^» t^^

8N
O

CO'-'O'-''!}'OOTt-Mi-ii-<
tOOO i-i rj- t-» O TfOO N VO
••« N Tf" vr.vo OO ON O N CO
vo to vo vo to vo vovo vovo

COI^-M ONOO OO ON C^ t^. ^

O Tf- CN COOO COOO T*- ON vo

VOVQ t^ ON O M CO vovo OO

vovovot^r^. t^.r^t^.t>-t>«

J,UI«IQ

OOOOOOOOOO COOOOO

RICHARDS' STEAM-ENGINE INDICATOR.

Circumferences of Circles, advancing by lOths.

CIRCUMFERENCES.

•3

•4

•S

-7

•9

.00

.31

.62

•94

I 25

•1-57

1.88 2.19

2.51

2.82

3.14

3-45

3.76

4.08

4.39

4.71

5-02 5.34

5.65

5 96

2 6.28

6 59

6.91 7.22

7-53

7 85

8.16 8.48

8.79

9.11

3 9.42

9.73 10.05 10.3610.68

10.9

11.30

11.62

ii 93

12.25

412.56

12.88^3. 19 13.50 13.82

14-13

H 45

14.76 15.07

15 39

5 I5-7O

16.02 16.33

16.65 16.96

17.27

17-59

17.90 l8.22

18.53

618.84

19.1619 47

19.7920. 10

20.42

20.73

21.04

21.36

21.67

721.99

22.3022.61

22.9323.24

23.5623^,87

24.1924.5024 Si

825.13

25 4425.7626.07

26.3826.7027.01

27-3327 6427.96

928.27

28.5828.9029.21

29-53

29.8430.15

30.4730.7831.10

1031.41

31.7332-0432.35

32.67

32.9833 3033-61

33-92

34.24

"34-55

34.8735.18

35.50

35-81

36.1236.44

36.75

37-07

37.38

1237.69

38.0138.32

38.64

38.95

39.27

39.5839-8940.2i

40.52

1340.84

41.1541.46

41.78

42.09

42.41

42.72

43-0343-35

43-66

I443-98
1547.12

44.2944.61
47-4347-75

44.9245.23
48.0648.38

45.5545.86
48.6949.00

46.1846.49
49.3249.63

46.80
49 95

1650.26

50. 57' 50. 89

51.20

5I-52

5i 83

52.15

52.4652.77

53-09

1753 40

53.7254.03

54-34

54-6054.97

55-29

55.6055.92

56-23

1856.54

56.86,57/17

57-49

57.80

58.11

58.43

58.74 59.O6

59-37

1959.69

60.0060.31

60 63

60.94

61.2661.57

6l.8862.20

62.51

20 62 . 83

63.1463.46

63-77

64.08

64.4064.71

65.0365.34

65.65

2165.97

66.28

66.60

66.79

67.29

67.54

67-85

68.17

68.48

68.80

2269.11

69 42

69.74

70.05

70 37

70.68

71 oo

7L3I

71.62

71.9^

72.25

72-57

72.88

73-19

73. 51

73.82

74 14

74-45

74.76

75 °8

75 39

75-71

76.O2

76.34

76.65

76.96

77.28

77-59

77.91

78.22

78 54

78 85

79.16

79.48

79-79

80. ii

80.42

80.73

81.05

81.36

26
27
28

81.68
84.82
87.96

81.99

85-13
88.27

82.30
85.45

88.59

82.62
85.76
88.90

82.93
86.07
89.22

89-53

83.56
86.70
89.84

83.88
87.02
90.16

84.19
87-33
90.47

84-50
87.65
90-79

91. 10

91.42

9i 73

92.04

92.36

92.67

92.99

93.30

936i

93-93

94.24

94-56

94.87

95.19

95-50

95 81

96-13

96.44

96.76

97.07

97.38

97.70

98.01

98.33

9864

98.9699.27

99-58

99.90

100.2

100.5

100.8

IOI.I

101.4

101.7

102. I 102.4

102.7

103 o

i°3 •;

33
34

103.6
106.8

103.9
107.1

104.3
107.4

104.6
107.7

104.9
108.0

105.2 105 5
108.3 Io8 •(•

105.8

109.0

106.1
109.3

109.6

35109-9

no. 2

110.5

no 8

III. 2

111.5 in. 8

112. I

112.4

II2-7

RICHARDS STEAM-ENGINE INDICATOR.

Circumferences of Circles, advancing by lOths.

Diameter. |

CIRCUMFERENCES.

•4

-7

113.0

II3-4

II3-7

114.0

114.3 II4.6

II4.9

II5.2

IIS-6

H5-9

116.2

116.5

II6.8

117.1

117.4 117.8 118. 1

II8.4

II8.7

119.0

119.3

II9.6

120.0

120.3

120.6 120.9

121. 2

I2I.5

121. 8

122.2

122.5

122.8

I23.I

123.4

123.7:124.0

124.4

124.7

125.0

125-3

125.6125.9

126.2 126.6

I26.9|I27.2

127.5

127.8

128.1

128.4

128.8129.1

129.4 I29«7

I30.0I30.3

130.6 I3I.O

131.3

I3I.6

131.9:132.2

132.5132.8

I33-2I33.5

I33-8I34.I

134.4

134.7

135.0135.4

135.7136.0

136.31136.6

I36.9I37.2

137.6

137.9

138.2138.5

138.8 139.1

139.4139.8

I40.I 140.4

140.7

I4I.O

141.3 141.6

142.0

142.3

142.6142.9^43.21143.5

143.8

I44.I

144-5144-8

I45-1

145-4

145.7146.0146.3 146.7

147.0

147-3

147-6147-9

148.2

148.5

148.9 149.2

I49.5I49.8

150. 1

150.4

48
49

150.7,151.1
153-9154.2

I5I-4
154-5

151-7
154.8

I52.O
I55-I

152-3
155-5

I52.6I52.9
155.8 I56.I

15^.3

156.4

153-6
156.7

5°

157.0157.3

157-7

158.0

158.3

158-6

158.9

159.2

159.5

159.9

160.2

160.5

160.8

161.1

161.4

161.7

I62.I

162.4

162.7

163.0

163.3163.6

163.9

164.3

164.6 164.9 165.2

165.5

165.8

I66.I

i66.5!i66.8

167.1

167.4

167.7 168.0 168.3

168.7

169.0

169.3

169.6

169.9

170.2

170.5

170.9171.2

I7L5

I7I.8

172.1

172.4

172.7

I73.I

173-4

173-7

174.0174.3

174.6

174.9

175.3

175.6

175-9

176.2

176-5

176.8

177.1

177-5

177.8

I78.I

178.4

178.7

179.0

179.3

179.6

180.0

180.3

180.6

180.9

181.2

181.5

181.8

182.2

182.5

182.8

183.1

183.4

183-7

184.0

184.4

184.7

185.0

185-3

185.6

185.9

186.2

186.6

186.9

187.2

187.5

187.8

188.1

188.4

188.8

189.1

189.4

189.7

190.0190.3

190.6

191.0

191-3

191.6

I9I.9

192.2

192.5192.8

193.2

193-5

193.8

194.1

194.4

194.7

I95.O

195-4

195.7196.0

196.3

196.6

196.9

197.2

197.6

197.9

198.2

198.5

198.8199.1

199.4

199.8

200.1

200.4

200.7

201.0

201.3

201.6

202.0

202.3

202.6

202.9

203.2203.5

203.8

204.2

204.5

204.8

205.1

205.4

205.7

206.O

206.4206.7

207.0

207-3

207.6

207.9

208.2

208.6

208.9

2O9.2

209-5J209.8

210. I

210-4

2I0.82II.I

211.4211.7

212.0

212.3

212.6213.0

213-3

213.6

2I3.92I4.2

214.5214.8

2I5.I

215-5

2i5.8'2i6.i

216-4

216.7

2I7.02I7.3

217.7218.0

218-3

218.6

218.9 219.2

219.5

219.9

22O.2|220.5

220.8'22I. I

221.4

221. 7 222. 1 '222. 4

222.7

RICHARDS STEAM-ENGINE INDICATOR.

Circumferences of Circles, advancing by lOths.

Diameter.

CIRCUMFERENCES.

• 3

•4

•5

•7

. .8

-9

223.0

223.3

223.6

223.9224.3

224.6224.9

225.2

225.5225 8

72 226. 1

226.5

226.8227.1227.4227.7228.0

228.3

228. 7^29. o

73229-3

229.6

229.9 230. 2 230. 5(230.9 231 . 2

231.5231.8232.1!

74232.4

232.7

233-1

233-4233-7

234.0234.3

234.6234.9235.3

75235 6235.9

236.2

236.5236.8

237-I237-5

237 8238.1238.4

76:238.7239-0

239-3239-7

24O.O

240.3240.6

240.9

241.2241.5

77241.9

242.2242.5242.8243.1

243 . 4 243 . 7

244.1

244.4244.7

245-0245.3245 61 245. 9 246 3

246.6246.9

247.2

247.5247.8

248.1 248.5248.8249. 1)249.4

249.7

250.0

250.3

250.6251.0

251.3251.6

25I-9252.2252.5

252.8

253.2

253-5

253.8254.1

254.4

254.7255.0255.4255.7

256.0236.3

256.6

256.9257.2

257.6257.9258.2258.5258.8

259.8

260.1

260.4

83
84
85

260.7
263.8
267.0

261.0261.3261.6262.0
264 . 2 264 . 5 264 . 8 265 . i
267 . 3 267 . 6 267 . 9*268 . 2

262.3262.6
265.4265 7
268.6268.9

262.9
266.0
269.2

263.2263.5
266.4266.7

269.5269.8

270.1

270.4270.8271.1271.4271.71272.0

272.3

272.6273.0

273-3

273-6273.9274.2274.5274.81275.2

275 5

275.8

276.1

276.4

276.7277.0

277.4277.7278 0278.3

278.6

278.9279.2

279.6

279.9280.2

280.5280.8281.!

281.4

281.8

282.1282.4

282.7

283.0283.3

283.6284.0284.3

284.6284.9

285.2285.5,

285.8

286.1286.5

286.8287.1287.4

287.7288.0

288.3

288.7

289.0

289.3289.6

289.9290.2290.5

29O-9!29I.2

291.5

291.8

292.1

292 4292.7

293-1293.4293 7

294.0294.3

294.6

294.9

94
95

295-3
298.4

295 6295.9
298.7299.0

296.2
299-3

296.5296 8
299.7300.0

297.11297-5

300.31300.6

297.8
300.9

298.1
301.2

301.5

301.9302.2

302.5

302.8303.1

303.4

303-7

304-*

304-4

97
98

304 7
307.8

305-0305-3
308.1308.5

305 6
308.8

305.9306.3
309.1309.4

306.6
309 7

306.9
310.0

307.2
310.3

307-5
310.7

100

311.0
3H i

311 33" 6
314 4314.7

3" 9

315 -i

312.2312.5
3I5-43I5-7

312.9
316.0

313 2
316.3

313.5

316.6

313.8
316.9

RICHARDS' STEAM-ENGINE INDICATOR.

If the areas of larger cylinders are required, they
will be found by the following RULE : — Multiply the
square of the diameter by the decimal .7854, and
the product will be the area in square inches ;
or, multiply half the circumference by half the
diameter.

TABLE No. IL

Showing the weight of the atmosphere, in Ibs. avoirdupois, on 1
'square inch, corresponding with different heights of the barom-
eter, from 28 inches to 31 inches, varying by tenths of an
inch.

Barometer
in Inches.

Atmosphere
in Ibs.

Barometer
in Inches.

Atmosphere
in Ibs.

!
! Barometer
I in Inches.

Atmosphere
in Ibs.

28.0

13.72

29.1

14.26

i
30.1

14-75

28.1

13-77

29.2

H.3I

30.2

14.80

28.2

13.82

29-3

14.36

30.3

14 85

28.3

I3-87

29.4

14.41

30-4

14.90

28.4

13.92

29.5

14.46

30-5

14.95

28.5

13 97

29.6

14.51

30.6

15.00

28.6

14.02

29.7

14.56

30-7

I5-05

28.7

14.07

29.8

14.61

30.8

15.10

28.8

14 12

29.0

14.66

30-9

15-15

28.9

14.17

30.0

14.70

31.0

I5-I9

29.0

14.21

RICHARDS' STEAM-ENGINE INDICATOR.

Elastic force in

Inches

Pounds

Tempe-
rature.

Volume.

Inches

Pounds

Tempe-
rature.

Volume.

per

Merc'y.

Sq. In,

Merc'y .

Sq. in.

193.82

95-

328.2

310

306.

150.

363.4

205

203.99
214.19

100.

105.

332.
335-8

295
282

316.19 155-
326.39! 1 60.

366.
368.7

198
193

224.39

no.

339.2

271

336. 59( 165.

37I-I

187

234.59

ii5-

342.7

259

346.^9 170.

373-6

I82

244.79

120.

345-8

251

357- 175.

376.

178

254-99

125-

349-1

240

367.2

180.

378.4

174

265 19

130.

352-1

233

377-1

185.

380.6

169

275-39

135-

355-

224

387.6

190.

382.9

166

285.59
295-79

140.

145-

357-9
360.6

218
2IO

397-8
408.

195-

200.

384.7
387-3

161
158

TABLE No. IV.

No.

Logarithm.

No.

Logarithm.

No.

Logarithm.

1.25

.22314

.60943

9-5

2.25129

i-5

.40546

5.25

. 65822

10.

2.30258

i 75

.55961

5-5

.70474

II.

2.39789

2.
2.25

.69314
.81093

I:75

.74919
•79175

12.
13-

2.48490
2.56494

2-5

2-75

.91629
.OIl6o

625
6.5

•83258
.87180

14.
15.

2.63905

.09861

6.75

.90954

16.

2.77258

3 25

.17865

•94591

17-

2.83321

3-5

•25276

7^25

.98100

18.

2.89037

3 75

.32175

7-5

2.01490

19.

2-94443

.38629

7-75

2.04769

20.

2-99573

4-25

.44691

2.07944

21.

3-04452

4-5

4-75

.50507
•55814

8.5
9-

2.14006
2.19722

22.

3.09104

RICHARDS STEAM-ENGINE INDICATOR.

TABLE No. V.

Table of Steam used Expansively.

Average Pressure of steam in Ibs, per. square inch for the

•whole stroke.

Initial

Pressure,
Ibs. per

Portion of stroke at which steam is cut off.

square inch.

4.8

4.6

4.2

3-7

2-9

i.9

9.6

9.1

8.4

7-4

5-9

3-8

14.4

13-7

12.7

11. i

8.9

5-7

19.2

18.3

16.9

14.8

11.9

7-6

24.1

22.9

21. 1

18.5

14.9

28.9

27-5

25.4

22.2

17.9

ii 5

33-8

32.1

29.6

25.9

20.8

13 4

37-5

36.7

33-8

29.6

23.8

15.4

fti

57-8

4i-3
45-9

42-3
50-7

33-3
37-o
44-5

26.8
29.8
35-7

17.3
19.2

67.4

64.3

59«2

52-4

41 -7

26.9

80
90

86*. 7

67.7
76.1

47-7
53 6

30-8
34 6

100

96*3

91.8

84.6

74-i

59.6

38.4

106.0

IOI.O

93«i

81.5

65.6

42.5

120

115.2

no. 2

101.5

89.4

7i-5

46.1

130
140

125.4
134.9

119.1
128.6

IIO.O

118.5

95-3
103.8

77-5
83-3

50.0
53-8

144.7
153-6

137-8
147.0

126.4
135.4

III 2

118.2

89-4
95-4

57-7
61.5

1 80
200

173-5
192.7

164.6
183-7

152-3
169.3

132.9
148.3

107.3

76*9

54 KICHARDS STEAM-ENGINE INDICATOR.

We insert the Table No. Y, not for general use in
•determining the mean pressure, as we have seen in
the example on page 62, that another element, the
clearance, has to be taken into account to get a cor-
rect result. Now, it is seldom we can get at the
drawings or patterns to get the measurement of the
clearance, hence we must seek some other mode.

We can easily find if the engine is tight or not, by
taking off the cylinder cover, putting the engine on
the half stroke, blocking the fly-wheel, and letting
«team on the opposite side of the piston. Suppose
we find it tight in valves and piston, we then replace
the cover and take some diagrams, and find the
mean by measurement, as directed on page 62. We
then refer to the table for the mean pressure, which
will be found too low when compared with the result
l>y measurement. Then, this excess given by meas-
urement over the table is approximately the clear-
ance.

The editor is responsible for the above. He is
;aware that it is, at best, but an approximation., owing
to the condition of the steam, whether wet or dry,
influenced, also, by the point of cut-off, pressure of
.steam, etc. The engineer has to adopt this mode,
or guess, or he may avail himself of both.

Where time and circumstances permit, the clear-
ance may be accurately found, if the piston is tight,
as follows: Put the engine on the centre, remove
iihe cover of the valve chest, uncover the steam-
port on the end where the piston is, and pour in

RICHARDS STEAM-ENGINE INDICATOR. 9£

water until it is filled level with the valve seat; wait
a few minutes, and if it maintains its level we know
it is tight; then draw off the water, measure or~
weigh it, reduce it to cubic inches, and we have it
exactly. Should the piston leak, we remove it out
of our way; cut a segment from soft wood of suffi-
cient length and width to cover the port at its
entrance to the cylinder, fasten it in its place, and
fill with water as above. To this must be added
the clearance between piston, when on the centre
and cover.

Again, the clearance being known and added,
we compute them by measurement. If the mean
pressure falls short of that, we know that there is
a leak in the exhaust valves or piston. If it over-
runs that, we know the cut-off valves leak. Hence
the utility of the table is to make those point*
manifest.*

Cu'

&rf

CAUFr'**'

RICHARDS' STEAM-ENGINE INDICATOR.
DIAGRAM No. 0.

RICHARDS' STEAM-ENGINE INDICATOR. 99

DIAGRAM No. 1.

Scale, 12 Ibs. to the inch.

RICHARDS' STEAM-ENGINE INDICATOR. 101

DIAGRAM No. 2.

200 revolutions per minute. 132 Ibs. pressure of steam cut
off at second notch.

RICHARDS' STEAM-ENGINE INDICATOR. 103

DIAGRAM No. 3.

200 revolutions per minute. 109 Ibs. pressure of steam cut
off at second notch.

&.'

ji> ,R 6 1 T Y

^^(.:

RICHARDS' STEAM-ENGINE INDICATOR. 105

DIAGRAM No. 4.

revolutions per minute. 105 Ibs. pressure of steam cut
off at first notch.

RICHARDS' STEAM-ENGINE INDICATOR. . 107
DIAGRAM No. 5.

224 revolutions per minute. 107 Ibs. pressure of steam cut
oft' at first not cli.

RICHARDS' STEAK-ENGINE INDICATOR. 109

TVEBSIT* J

\,C

BICHARDS' STEAM-ENGINE INDICATOR. Ill

DIAGRAM No. 7.

A, termination of correct, expansion curve.

RICHARDS STEAM-ENGINE INDICATOR.

DIAGRAM No. 8.

113

RICHARDS' STEAM-ENGINE INDICATOR. 115

No. 9.

RICHARDS' STEAM-ENGINE INDICATOR. 117

DIAGRAM No. 10.

BICHABDS' STEAM-ENGINE INDICATOR.

119

DIAGRAM No. II.

Of THE

XJNIVEESITT

BICHARDS' STEAM-ENGINE INDICATOR. 121

DIAGRAM No. 12.

BICHAUDS' STEAM-ENGINE INDICATOR. 123

DIAGRAM No. 13.

KICHAItDS' STEAM-ENGINE INDICATOR. 125

DIAGRAM No. 14.

RICHARDS' STEAM-ENGINE INDICATOR.
DIAGRAM No. 15.

127

[( UNIT -{ »

B1OHARDS' STEAM-ENGINE INDICATOR.

DIAGRAM No. 16.

BICHABDS' STEAM-ENGINE INDICATOR.
DIAGRAM No. 17.

BICH ABBS' STEAM-ENGINE INDICATOR.

DZAORAXKI No. 18.

133,

?BIT

> 1

EICIIARDo' STEAM-ENGINE INDICATOR. 135

DIAGRABI No. 19.

Back and forward.

RICHARDS' STEAM-ENGINE INDICATOR. 137

DIAGRAM No. 20.

RICHAliDS' STEAM-ENGINE WlCA3$£\f < 139

DIAGRAM No. 21.

RICHARDS STEAM-ENGINE INDICATOR.

DIAGRAM No. 22.

141

RICHARDS' STEAM-ENGINE INDICATOR.

143

APPENDIX.

USEFUL INFORMATION.

Cement for Steam Joints.

Take a quantity of pure red lead, put it in an
iron mortar or on a block or thick plate of iron.
Put a quantity of pure white lead ground in oil;
knead them together until you make a thick putty,
then po?md it ; the more it is pounded the softer it
will become. Koll in red lead and pound again ;
repeat the operation, adding red lead and pound-
ing until the mass becomes a good stiff putty. In
applying it to the flange, it is well to put a thin
grummet around the orifice of the pipe to prevent
the cement being forced inward to the pipe when
the bolts are screwed up. The more pounding the
better.

Another, to be used when the flanges are not
faced : Make the above mass rather soft and add
cast-iron borings, pounding in thoroughly until it is
sufficiently soft to spread.

Both the above are the most durable cements
known to the engineer. They will resist fire and
set in water.

140 RICHARDS' STEAM-ENGINE INDICATOR.

Another (English), said to be very good : Take
10 Ibs. ground litharge, 4 Ibs. ground Paris white,
\ Ib. yellow ochre, J oz. of hemp cut into lengths of
J';; mix all together with boiled linseed oil to the
consistence of a stiff putty. Resists fire and will
set in water. [Pounding would improve it. — ED.]

A Good Dressing for Leather Belts.

One part of beef kidney tallow and two parts of
castor oil, well mixed and applied warm. It will
be well to moisten the belt before applying it.

No rats or other vermin will touch a belt after
one application of the oil. It makes the belt soft,
and has sufficient gum in it to give a good adhesive
surface to hold well without being sticky.

A belt with a given tension will drive 34 per cent,
more with the grain or hair side to the pulley than
the flesh or rough side.

Rules for Calculating Belting.

This is one of the most difficult problems the
engineer has to solve. There are so many different
conditions attending the conveying of power by belts
that no definite rule can be given. I have found,
however, that where the conditions are fair to mid-
dling, that a belt one inch wide, running 800 feet
per minute, is equal to one horse power. Increased
width in proportion. This will do the work under
a safe and proper tension. There are conditions,

RICHARDS' STEAM-ENGINE INDICATOR. 147

however, which might require double the above
width or speed.

How to make belts run on the centres of pulleys.

It often happens that a belt will persist in run-
ning on one side of the pulley.

In this case one or more things cause it. First,
one or both of them may be conical, and of course
the belt would run on the higher side. Second, the
shafts may not be parallel ; in this case the belt
would incline off, on the side towards where the
ends of the shaft are nearest to each other. The
remedy in this case is, to make them parallel to
each other by carrying the ends of the shaft towards
which the belt inclines, farther apart.

In giving rules for calculating the horse-power of
belts, we would not be understood as saying that a
belt will not do more than the rule would give ; on
the contrary, we know that double and even more
power may be transmitted by them by a sufficient
tension, which would create a ruinous amount of
friction and a speedy destruction of the belt. "We
would be understood to say that the rules give data
for a belt that will run with a moderate and safe
tension. The attempt often made to calculate the
work that a belt of given width and travel in feet
per minute without any known tension is doing, or
will do, is very like comparing the size of a pebble-
stone to a piece of chalk. The Indicator tests that
with certainty.

148 RICHARDS' STEAM-ENGINE INDICATOR.

The practice of putting an idler against a belt to
make it drive is a most pernicious one, destructive
alike to the belt and power ; its only merit is to
disguise bad engineering.

Measuring Steam used for heating.

The engineer is often called to determine the
amount of steam that is used to heat apartments,
liquids, etc. This the Indicator does not reveal
directly, no farther than it shows how much steam
it requires for a horse-power ; varied, of course, by
the point of cut-off and its efficiency.

Under these circumstances we have followed the
rule of Watt, which is to allow one cubic foot of
water per hour for each horse-power ; hence we
measure the water condensed in the heating pipes
in a given time, and estimate accordingly.

If it is inconvenient to reduce the water to cubic
feet, it may be weighed, allowing 62.5 Ibs. to the
cubic foot, or it may be measured by the gallon, or
7.48 gallons per cubic foot.

When the steam pipe enters the vessel and it dis-
charges the steam directly into the liquid to be
heated, the water then cannot be caught to be
measured ; in that case we measure the increment
of its contents, and thereby find the quantity of
steam condensed.

RICHARDS' STEAM-ENGINE INDICATOR.

Condensation of pipes and coils.

Steam pipes in the ordinary circulation, such as
are used to warm buildings, when one or more run
around the sides of the apartment, having and
maintaining a temperature of 60°, will condense
.357 Ibs. of water per hour for each square foot of
surface of pipe.

A coil maintaining the same temperature will
condense .29 Ibs. per hour per square foot of sur-
face.

The radiating surface of steam pipe required to warm
buildings and apartments.

This varies in consequence of the character of the
structures, the exposure, the quantity of glass,
the use the space required to be heated is put to,
climate, etc.

In the city of New York the data of calculation,
modified by the above-mentioned circumstances, is
this :

For dwellings — when the pipes in form of a coil
are placed in the cellar and supplied with air from
outside — one square foot of pipe surface to 50 cubic
feet of apartment to be warmed.

When the coil is placed in the apartment, one
square foot of surface of pipe to 65 cubic feet of
space.

In stores and warehouses, one square foot of pipe
surface to 175 to 200 cubic feet.

150 RICHARDS' STEAM-ENGINE INDICATOR.

In workshops, one square foot of pipe surface to
100 cubic feet of space.

Heating with exhaust steam is of questionable
economy. It is not economical, certainly, when
used in small pipes, in consequence of the power
required to force the steam through them. We
have seen exhaust steam used economically in work-
shops and factories where it is permissible to use
large cast-iron pipes, which present so much less
friction surface in proportion to the area, that the
power used to force the steam into them shows but
a small back pressure on the engine — 1 or 1| lfos. per
square inch — if the pipes are of sufficient size and
properly arranged. We have found the following
to work well in practice :

We use for the smallest, flanged pipe, without re-
gard to the size of the engine, 4" diameter. If it
is required to be over 75 feet in length, we use 5" ;
if over 100 feet, we use 6".

The pipes should be f thick, with flanges at
least 4 inches larger than the outside diameter of
the pipe.

These flanges should be faced so as to have a fair
bearing over the whole surface, and when faced, not
less, than f" thick, fastened with five bolts, I" diame-
ter. We place them, when practicable, around the
walls of the room, near the floor, on the sides most
exposed, giving them an inclination of not less than
one inch in ten feet ; for our joints, the cement No. 1
(rubber not permissible).

RICHARDS' STEAM-ENGINE INDICATOR. 15J

The main exhaust pipe we carry out of the build-
ing, without reference to our heating pipes, except
to have a nozzle to carry off steam to the highest
end of the heating pipe. Should there be one or
more rooms above or below, separate pipes fron*
the main should be led off in the same way. The?
drain pipes should be at the lowest end of the piper
and J" to |" diameter. If it is desirable to let
only water escape, a siphon may be fixed to the-
end of the tail pipe, with legs of sufficient length
to overbalance the steam pressure, yet leaving the-
water by its superior gravity to escape.

The supports should be firmly fixed to the wallr
in perfect line with each other, that there be no>
bend or low place for the water to collect, which
would inevitably destroy the pipe.

We have used a system of pipes arranged as
above, for eight years, without the least attention
to them-. Not a joint Jias leaked.

Since the publication of the first edition, I have
seen exhaust steam used in 1J-" pipes with good re-
sult, and with but little back pressure. The arrange-
ment was to take the steam off the main pipe inta
4 — 4J" pipe, from the right and left side, carried
around on each side of the rooms. At the termina-
tion of each coil, a pipe 2" diameter carried off the
water and uncondensed steam. The back pressure-
shown was less than 2 Ibs.

It is not safe to allow steam pipes in contact with
wood.

152 RICHARDS' STEAM-ENGINE INDICATOR.

Value of Pea and Dust Coal, as compared with lump
of good merchantable quality, with a blast induced
by " Hancock's Steam Blower."

2,000 Ibs. of pea and dust, the screenings from
the coal-yards, have been found equal to 1,600 Ibs.
of lump. This is a result of several weeks' trial
with the same engine and boiler doing the same
work.

Gauge glasses, when required. -to be cleaned,
should have a wooden swab-stick. A metallic one
will cause the tube to fall to pieces inevitably, and
sometimes immediately.

Value of Cumberland coal as compared with
anthracite. Two tons (4,000 Ibs.) of anthracite
furnished steam for an engine seven days. The
same amount of Cumberland served the same
engine, everything else the same, eight days.

This experiment was continued with alternate
changes for two months.

Boiler, locomotive type, with natural draft.

When there are indications of an extraordinary
corrosion of the steam-boiler and its fittings, the
gauge-cocks and valves leak. Acid is suspected.
Test it by putting into a sample of the water a strip
of litmus paper ; if acid 'is present, the purple paper
will be changed to red.

RICHARDS' STEAM-ENGINE INDICATOR. 153

To ascertain if iron is in solution, put into the
samples a few grains of tannic acid ; if iron is
present, it will immediately become a dark purple or
black.

The writer has found two cases where the wells
that supplied steam-boilers were poisoned by the
spent irickle finding its way into the wells, thence to
the boilers, and was detected as above. The iron
(sulphate) was so abundant, when a proper quantity
of tannin was put in, it formed a sufficient ink so
that the report of the examination was written with
it. F. W. B.

Water when converted into steam can heat about
6 times its own weight of well water to 212° Fahr.

JAMES WATT.

Sir Wm. Fairbairn found, by a series of experi-
ments, that in constructing internal flues for boilers,
when the pressure was from outward to the center
(centripetal), that as the length was increased, the
thickness of plate must be increased in direct pro-
portion. That is, if £-inch plate was right for a
10 ft. length, if the flue was 20 ft. in length, the
plate must be i inch to stand the same pressure.

Dressing for an Emery Wheel, to give a fair polish, say
such as is usual on carpenter's tools.

The tool has been surfaced on a wheel covered
with No. 60 emerv. Take another wheel covered

154 RICHARDS' STEAM-ENGINE INDICATOR.

same No., and rub on a composition of flour,
•emery and beeswax. Set the wheel running and
hold on a flint ; again rub on the composition and
.again the flint, until it gives the polish required.

To make the composition, melt the wax with a
gentle heat ; stir the emery in until it is thick ;
Temove the heat, and keep up the stirring until it is
.-so cool that the emery won't fall to the bottom.

The wheel must be kept nicely balanced, or the
polish will be cloudy. F. W. B.

To Cool Off a Hot Bearing.

Take off the top box, and while the shaft is slowly
turning, put on white-lead ground in oil from the
leg. When the lead is seen coating the bearing as
it turns slowly, it shows that the lead has interposed
itself between the two surfaces and will cool down,
when the ordinary lubricant may be resumed.

F. W. B.

Water j Scales the Boiler. Lime is suspected.

TEST. — Into a tumbler containing the suspected
water put 8 or 10 grains of oxalic acid ; if lime is
present, the water will become milky, and after
standing quiet awhile, the lime will be precipitated
•(oxalate of lime).

Should the precipitate not show itself, add a little
ammonia, which is a more delicate test. If no pre-
cipitate is shown, it is not lime that forms the scale.

F. W. B.

RICHAliDS' STEAM-ENGINE INDICATOR. 155

For Calculating the Horse-powers of a Given Quantity
of Water in a Given Time, 7,000,000 gallons of Water
passing through the Turbine in 60 hours.

KULE. — Multiply the fall in feet by .3682. The
product is the horse -powers, net. This is a unit. If
there is more or less water, or more or less time, the
horse-power developed will be more or less in direct
proportion.

From testimony of J. B. FRANCIS, C. E.

ANOTHER RULE. — 8.8 cubic feet of water per second
falling one foot is equal to one horse-power.

From testimony of C. HERSCHEL, C. E.

The Inspirator

supplies the steam-boiler with water cheaper than the
steam-pump. F. W. B.

Memorandum.

It is bad practice to pack the joints of steam-
chests, cylinder-heads, etc., with rubber ; in fact, any
joint that is exposed to heat, as the sulphur used in
volcanizing, disintegrates the cast iron and erodes
the bolts inevitably in tim?. It may be tolerated in
the manhole of the boiler. F. W. B.

RICHARDS-THOMPSON'S STEAM-ENGINE INDICATOR.

156

SUPPLEMENT

TO THE

PORTER-BACON TREATISE ON THE

EICHARDS STEAM-ENGINE INDICATOR;

BEING NOTES ON THE

RICHARDS-THOMPSON INDICATOR,

THE AMSLER POLAR-PLANIMETER AND THE PANTOGRAPH,
AS USED IN CONNECTION WITH THE INDICATOR.

By F. W. BACON, M. E.,
Member of the American Society of Civil Engineers.

1879.

157

THE

RICHARDS-THOMPSON

STEAM-ENGINE INDICATOR,

rTIHE constant demand for high piston speed of
-A- stationary and locomotive engines, has outrun
the capacity even of the Kichards instrument, and
rendered it imperative, if we would have a correct
result, that an instrument be produced that would
meet the call. Therefore, "necessity being the
mother of invention," the patentee has given us the
instrument which is all that can be desired. It is
believed that it will give correct results under any
attainable speed of a steam-engine. It will be ob-
served that Mr. Thompson's improvement mainly
consists in reducing the weight 43.65 per cent of
the parallel motion, by reducing the number of
vibrating pieces, thereby reducing the tendency to
make wavy lines in both steam and expansion. By
the new arrangement the instrument is lighter and
more compact, qualities that will be fully appreciated
by the engineer.

159

160 RICHARDS-THOMPSON INDICATOR.

With these improvements, and the facilities pro-
vided for the attachment of the instrument, it is
obvious that the engineer in charge should be edu-
cated to its use, and required to make weekly reports
of power indicated and fuel expended.

The Indicator is the light to the engineer's eye :
without it he gropes in the dark ; he can't set his
valves correctly ; he has no mode of measuring the
power even approximately without it ; hence he can
make no comparative test of fuel used and power
eliminated ; he may be burning 10 or 15 Ibs. of coal
per hour per horse-power, when he should burn but
2J to 3 Ibs. per hour per horse-power ; a most scan-
dalous and wicked waste of fuel.

The locomotive presents a great field for its appli-
cation, though as yet but partially cultivated. Those
master mechanics who have had the courage to apply
it, and have followed its indications, have shown
most curious results, which have prompted a change
in valve gear, valve settings, enlargements of ports
and thoroughfares, an increase in the areas of noz-
zles, etc.

The following diagram (No. 1), taken by J. A.
Lauder, Esq., M. M., of the Northern (N. H.) Rail-
road, is one of the many taken from engines under
his charge, which he has kindly furnished me ; it is
not an exceptional one. It will, however, be hard to
find its superior. To attain this excellence, he fol-
lowed the dictation of the Indicator. Its mate from
the other end is o.fac-simile.

BICHARDS-THOMPSON INDICATOR.

162 RICHARDS-THOMPSON INDICATOR.

The LOCOMOTIVE, MOGUL PATTERN, of the following
description :

WOOD BURNER.

Cylinders, 17 x 24 in. ; diameter of wheel, 54 in. ;
admission ports, 16x1^ in.; exhaust ports, 16 x 2 j
in.; outside lap, -J in.; inside lap, -J- in.; travel of
valve, 5 in.; lead full gear, ^ in. ; boiler pressure,
1 30 Ibs. ; cutting off at 12 in. ; exhaust nozzles, two,
3 in. diameter ; revolutions, 50 per minute ; scale of
instrument, 60 to one inch.

DIAGRAM NO. 2

is introduced to supply information to beginners, who
will sometimes, when getting diagrams from engines
without any or but little load, find the expansion
curve fall below the atmospheric line, showing a
partial vacuum behind the piston, and are often at
loss how to account for, or what to do with it.
The writer does not remember having seen it men-
tioned in any of the books, and having known of
some rather ridiculous blunders made in disposing
of it, ventures to take it up and explain it, though it
may seem to the expert unnecessary.

This " loop below " is made by the advancing piston
passing the point due to reducing the volume of steam
by expansion to the atmospheric pressure — at that
point the expansion-curve crosses the atmospheric
line, and might, under certain circumstances, create

RICHARDS-THOMPSON INDICATOR.

nearly a perfect vacuum, were it not for the presence
of water, which re-evaporates and partially fills the
space.

In treating this loop, it must be measured out, the
same as any back or negative pressure. It don't
suffice not to measure it in — measure the diagram
without including it, then measure it, and deduct it
from the sum of first measurement. This " loop "
incidentally serves a very important purpose, inso-
much as its presence shows that there is no leak
either in the valves or piston. 9

EICHAKDS-THOMPSON INDICATOR.

DIAGRAM No. 2.

RICHARDS-THOMPSON INDICATOB. 165

The following diagram (No. 3) is introduced as
one of the most perfect that is obtained from a high-
pressure, non-condensing engine. It was taken with
the Thompson Indicator, actuated by the Panto-
graph, from " The Brown'' engine, 16" x 42 "x 60
revolutions, exhibited at the Fair of the Massachu-
setts Charitable Mechanic Association. When we
consider the speed of the piston, 420 ft. per minute,
the steam pressure, 67 Ibs., scale 40, we think un-
commonly perfect lines are shown, especially the
steam line and expansion curve. It shows also a-
most prompt and perfect action of the admission and
eduction valves ; the point of cut-off is sharp,
decided, and unmistakable, qualities that will be
fully appreciated by the engineer.

It is one of many hundred diagrams taken by
the writer from the engine during the exhibition,
all with the same characteristics.

Should any one wish to make the theoretic curve
around the diagram, we give in addition to the above
data the clearance, 2£ per cent.

166

RICHARDS-THOMPSON INDICATOR.

DIAGRAM No. 3-

RICHARDS-THOMPSON INDICATOR. 167

For reducing the motion of the piston to the
required length of the diagram, there are many
devices. The one most in use is a strip of board
suspended from the ceiling above, or carried off
horizontally, as circumstances dictate, and it often
requires considerable ingenuity to effect it without
too much cost ajid delay. The pendulum should be
not less than one and one-half the length of the piston-
stroke from the point of suspension to the point of
attachment to the cross-head ; if longer, say twice
the length of the stroke, it is better.

To find the point of attachment of the line leading
off to the indicator, the following is the

RULE. — Divide the length of piston-stroke in inches
by the required length of the diagram ; divide the
length of the pendulum in inches by the above quo-
tient, and this quotient is the distance in inches from
the point of suspension to the point of attachment
of the line, approximately.

EXAMPLE. — Stroke of piston, 36". Length of re-
quired diagram, 4.5". Length of pendulum, 54".

Then 36"-=-4.5 — 8. 54^8 = 6.75.

Or, 4.5 ) 36.0 ( 8

36.0

8 ) 54 ( 6.75" from point of suspension to
48 attachment of line.

60
56
40

168 RICHARDS-THOMPSON INDICATOR.

Tliis is approximate, but not mathematically cor-
Tect, owing to the arc of a circle described by both
^points of attachment, yet is considered sufficiently
.accurate for practical purposes. The pantograph
:gives us a correct result.

On page 24 of the "Treatise," and onward, the
question of the mode of giving mption to the Indi-
cator is discussed. Since that was published, there
has been a new mode applied, which is invaluable,
insomuch as it is mathematically correct, can be
applied in almost any case, renders long lines and
•carrying pulleys unnecessary, is compact and port-
able, being when folded about 18" long by 3" x 5".
It is known as the Indicator Pantograph. It is fur-
nished with or without the instrument, when
required. It is an old, well-known device, applied
to a new purpose.

If the Indicator is applied to the side of the cylin-
der, it enables us to use short cords, without the use
of carrying pulleys to lead the cord to the Indicator.
We would advise the operator to use the Raided
cord, as it is far less elastic.

A medal was awarded to the Indicator Pantograph
ut the late Mechanics' Fair of Massachusetts.

Since the second edition of the Treatise was pub-
lished, an instrument for measuring and computing
diagrams has been introduced. It can be used also
to measure any other irregular or regular form
within its compass. It is known as

AMSLEK'S POLAR-PLANIMETER.

170 AMSLER'S POLAB-PLANIMETER.

Its use greatly diminishes liability to error; and
the great aid it affords to the quick and accurate
computation of diagrams, renders its use indispensa-
ble, especially to engineer experts who are employed
to make special tests of long duration, where a thou-
sand, more or less, of diagrams are to be calculated.
Also to the ordinary engineer who takes indicator
cards for the purpose of adjusting his valves and
calculating the power of his engine ; no matter what
the shape of the diagram is, whether the lines and
curves are straight or jagged, waving or serrated,
the instrument follows them accurately and gives a
correct measurement.

It will be seen by the engraving that the instru-
ment has two legs, with a joint at the top like a pair
of dividers, with the right-hand leg shorter than its
mate ; to the short leg is attached a cylinder (7, with
a projecting flange, which revolves freely on its axis.
The cylinder is divided into ten grand divisions, and
marked 1—2—3—4—5—6—7—8—9—0. Now as
the wheel rolls around, each one of these divisions
represent one square inch. Each one of these grand
divisions is subdivided into ten spaces representing
one tenth of a square inch. But this is not fine
enough ; we want to measure hundredths. To effect
this, we use the Vernier scale, which in this case is a
segment of a circle, same diameter as the cylinder,
whose edges are put in juxtaposition with each other,
but allowing the latter to revolve without touching.
This segment has one grand division just correspond-

AMSLEB'S POLAR-PLANIMETEE. 171

ing to nine of the subdivisions on the cylinder. This
grand division is subdivided into ten spaces, and
marked 0 — 5—10. This segment is firmly fixed to
the head of the instrument, so that the edge of it
exactly corresponds with the edge of the revolving
cylinder. It is called the Vernier scale. With these
relative positions, the graduations come opposite
each other, but as the spaces are not the same on
each, it is evident that but one mark on each can be
opposite.

HOW TO USE THE INSTRUMENT.

Fasten the diagram to your drawing-board by pins
or springs ; alongside of it a half-sheet of fine
glazed paper for the wheel of the instrument to move
on. Place the needle-point A at a proper point on
the paper and the tracer B on a marked point of the
outline of diagram D; then raise the wheel C and
turn it until 0 on the cylinder corresponds with 0
on the vernier E, press lightly with a finger of the
left hand on the point A, and with the fingers of the
right hand take hold of the top of the tracer B, and
carefully follow the line in the direction of the hands
of a watch until it reaches the starting-point. WTe
now read the instrument. We find that 0 on the
cylinder has passed on from 0 on JS9 and 2 has passed
it. We write 2 (2 inches). We follow it by seeing
how much 2 has passed. We find it shows four
marks on the cylinder and a little more. We write

172 AMSLER'S POLAR-PLANIMETER.

4, which is r%. We now look for a mark on the
cylinder that corresponds with one on the Vernier E.
In this case we find the second mark from Vernier 0
corresponds with a mark on the cylinder. We write
2, being Tf 7. The reading then is thus, 2.42 square
inches, area of diagram. We now measure the length
of the diagram in inches, parallel to the atmospheric
line, which in this case is four inches. We now divide
the area by the length ; the quotient is the mean
height in inches of the diagram, which is .605 inches ;
this we multiply by the scale of the indicator, which
is thirty to the inch in this case ; the product gives
us 18.15 Ibs. mean pressure on each square inch of
the piston. The sum is thus :

4 ) 2.42
.605

18.150 Ibs., mean pressure.
Expressed thus :

2.42 -f- 4 = .605 x 30 = 18.15.

N. B. — If the diagram should measure more or
less than four inches in length, divide by what it
may be ; so also with the indicator scale, multiply
by what it is.

If the figure to be measured is a plan drawn to a
scale, we proceed as above to get the square inches ;
we find in this case the reading to be nine square
inches, our scale is one inch to one foot, which is

AMSLER'S 'POLAR PLANIMETER. 173

one-twelfth size ; to raise this to full size, we multi-
ply the reading by the square of the ratio, thus :
12 x 12 = 144 x 9 = 1296 square inches' full size.
Same in all other scales. Square the denominator and
multiply the product by the reading ; the product is
full size in square inches.

In giving in the foregoing direction how to read
the record of the instrument, we have supposed that
the operator was not familiar with the Vernier scale,
hence we advised him to put 0 and 0 to correspond ;
this is right, though not necessary.

FOR EXAMPLE : The instrument is in place, the
reading is 1.14, the tracer is carried around the out-
lines as directed, and the reading is 3.56 ; now we
subtract the first reading from the second, thus :

3.56 - 1.14 = 2.42 3.56

1.14
2~42

This the learner will soon get familiar with.

THE CARE OF THE INSTRUMENT.

It is exceedingly delicate ; it will not bear banging
like a horse-shoe, nor suffered to become foul. Care
must be taken that £he roller-wheel revolves perfectly
free end yet no looseness in its 'pivots, the same in all
the joints. Take great care that the roller-wheel
and vernier-scale don't get msty or foul with dirt.
Oil the movable points with porpoise oil and none

174

AMSLER S POLAR-PLAIslMETER.

other. It can always be procured at the watch or
clock maker's. This is imperative, if correct results
are to be attained.

The above description is believed to be sufficient
for all practical purposes. For a mathematical ex-
position, disclosing the scientific principles on which
it acts, see Spon's Dictionary.

For convenience in using the common rule to
measure the length of the diagram, we have calcu-
lated the following table, reducing the common
fraction to decimals :

Com.
Prac.

Decimal.)

Com.
Frac.

Decimal.

Com.
Frac.

Decimal.

Com.
Frac.

Decimal.

.0312

.2812

.5312

.7812

.0625

.3125 tV

.5625

.8125

.0937

.3437

.5977

.8437

.1250

.3750

.6250

.8750

.1562

.4062

.6562

.9062

.1875

.4375

•H

.6875

.9375

.2187

•H

.4687

.7187

.9687

.2500

.5000

.7500

1.0000

From the above description and examples it will
be seen that calculating the 'diagram is reduced to
the minimum of time and maximum of accuracy.
We dispense with the use of the parallel rule, with

AMSLER'S POLAE-PLANIMETEB. 175

ten or more measurements, with adding up a long
column of figures and the required divisions, to get
a doubtful result at best, and substitute the described
manipulation of the instrument ; note its reading,
and by the use of fourteen figures get a positively
accurate result.

DIRECTIONS.

Before taking the diagram, shut off the supply of
whatever lubricant is used in the cylinder of the
engine, which is usually some gummy oil or other
villainous compound, that gums the piston and
cylinder of the instrument, rendering its action
dull, showing curves where there should be angles,
and retarding its free action generally.

Oil the piston of the instrument often when in use,
and see. that the cylinder is smooth and clean, for
on these points depend largely the integrity of its
action and correctness of the diagrams.

TO SELECT A SPRING FOR A GIVEN PRESSURE.

EXAMPLE.— Boiler pressure, 75 Ibs. -f- 2.5 = 30.

It is good practice to use as low number as will do
for the pressure, so as to get the diagram on a large
scale.

INDEX TO SUPPLEMENT.

PAGE

Diagram No. 1. — Showing the Action of the Instrument,

Thompson's Indicator 160-161

Diagram No. 2. — With Explanation of the " loop below," 162

How to Treat it 163

Diagram No. 3.— Its Character 165

Kule for Reducing Motion of Piston to required Length

of Diagram 167

Indicator Pantograph 168

Amsler's Polar-Plani meter with Cut 168-169

Description of the Instrument 170

How to Use it 171

Examples 172-173

Care of the Instrument 173-174

Table for Reducing Common Fractions to Decimals 174

Directions 175

How to Select a Spring for a Given Pressure 175

INDEX.

PAGB

American Editor's Preface 7

Nature and Use of the Indicator. 9

Mode of proceeding to Find the Power a Tenant Uses. . 9

Analysis of Diagram No. 1 14

Truth of the Diagram 16

Conditions of a Correct Diagram . . . 16

Errors Liable 17

General Construction of the Indicator 18

Metallic Pencil 19

List of Springs 20

Practical Directions for Applying and Taking Care of the

Indicator 21

Giving Motion to the Paper 24

From what Points to Derive the Motion 25

" "• " " on Locomotves. . 27

on Oscillating En-
gines 28

How to Take a Diagram 29

To Connect the Cord 30

To Take the Diagram 31

Notes on Diagram 33

How to Keep the Indicator in Order 34

Note on the Importance of Proper Oil 34

How to Change the Springs 36

" Barrel Springs 36

1 ' Ascertain the Power Exerted by the Engine ... 37

On Diagrams from Condensing Engines 40

177

INDEX.

PAGE

Power Exerted by Engines as Per Diagram No. 1, with

Example 43

On Diagrams from Non-condensing Engines — Example. . 46
To Measure from the Diagram the Amount of Steam

Consumed 49

Observations on the Several Lines of the Diagram 51

Classifications of Engines, Steam Line 52

Full Stroke, Lap, Link, Independent, by Action of Gover-
nor on the Cut-off Valve, and according to the Work

by Throttle 52, 53

Prof. Tyndall's Experiments 57

Importance of Cutting-off quickly 60, 61

To find Mean Pressure by Hyperbolical Logarithms. . . 62

Remarks of the Editor — Examples 68, 64

Exhaust Line and Line of Counter Pressure 64

Compression Line 65

Theoretic Curve and its Uses ; How it is made ; Clear-
ance Defined 67, 68

Cards from a Caloric Engine 72

Trip from Wilmington to Philadelphia on Locomotive

No. 50, with Method of Operation 73

Valve Setting— How to set a Slide Valve 78

Remarks on Table V. — How to find if the Engine is
tight, and how to find the Clearance 94

TA.BLES.

Table No. I.— Areas of Circles 81

Circumferences of Circles 86

Table No. II.— Showing Weight of the Atmosphere at

different Heights of the Barometer 89

Table reducing common fractions to decimals 174

INDEX. 179

PAGE

Table No. III.— Showing the Elastic Force of Steam at

Different Temperatures 90

Table No. IV. —Logarithms 92

Table No. V. — Steam Used Expansively. Average Pres-
sure in Ibs. per square inch for the Whole Stroke. . . 93

Diagrams 97-143

Diagram No. 1. — Supplement 161

" 2.— " 164

" 3.— " . 166

Cement for Steam Joints 145

A Good Dressing for Leather Belts 146

Rules for Calculating Belting 146

How to Make Belts run on Centres of Pulleys 148

"Idlers" 149

Measuring Steam used for Heating 149

Condensation of Pipes and Coils . . 149

Radiating Surface of Steam-pipe required to Heat Build-
ings and Apartments . 148

Comparative Value of Pea and Dust Coal with Lump 152

" Cumberland and Anthracite 152

Cleaning Gauge of Glasses 152

Extraordinary Corrosion 152

To Ascertain if Iron is in Solution 153

Quantity of Steam to Heat a Given Quantity of Water. . 153

Farbairn's Experiment on Boiler Flues 153

Dressing for Emery Wheels 153

To Cool Hot Bearings 154

Scale in Boilers 154

Lime is Suspected. Test 154

Rule for Calculating Horse-powers of Water . .^ „ 155

The Inspirator ••••.. 155

Rubber Steam Joints (. . T. 155

ANOTHER edition, the fourth, of this work is called for,
which indicates that our working engineers are becoming
educated in the use of the Indicator to their great advantage
and the interest of their employers, who, as a rule, appreciate
the great advan-
tages made man-
ifest and tangi-
ble by its intelli-
gent use. Com-
bined with the
Fairbanks Scale
it shows them
unerringly how
much power they
get for a dollar
from the various
kinds of fuels in
use.

In our third
edition, page 168,
we noted the
pantograph,
which is now in
general use,
which is shown
in the engraving.
It is shown to be
connected with
the old-style hor-
izontal cross-
head, links held
fast by the lock-
nut of the gib

adjusting screw. THE PANTOGRAPH.

It will be seen that the link is by its joints capable of being
expanded or contracted in its opening from 0 to 3)£", §g

that it will embrace the largest Corliss vertical crosshead to
the smallest adjusting or other screw. There are some small
pieces go with it, to adjust and attach it, which the engineer
will at once see the
use of in its applica-
tion under the va-
rious kinds of en-
gines and positions
he finds them. We
have never seen an
engine that we could
not get an attach-
ment with it in ten
minutes. This link
attachment is a
small, simple affair,
can be carried in
the pocket, and is
equally convenient
and useful with the
ordinary mode of
reducing the motion
as with the panto-
graph. The link at-
tachment is applic-*
able to all engines —
horizontal, vertical,
inclined-rotary, or
oscillating. It is
known as BACON'S
PATENT PANTO-
GRAPH ATTACHMENT.
Notwithstanding
the facilities fur-
nished by the above
attachment in get-
ting the motion
from the crosshead
or other proper
point, still another
difficulty often oc-
curs which gives us
more or less trouble
to manage, and that is to lead the line off in the proper direc-
tion so as to give a correct result. Steam-pipes, exhaust-pipe^

and other obstructions incident to the structure of the engine,
often the contracted space allotted to it, and unforeseen awk-
ward conditions oft-
en with the old ar-
rangement,, render it
impossible to get the
line to run parallel
with the piston-rod
(a sine qua non)
without too many
carrying pulleys or
chafing the lines,
which must in any
event be avoided if
we would have cor-
rect results. Hap-
pily the patentee has
helped us out of this,
as the accompanying
cats will show.

Fig. 1 shows the
original Thompson
instrument. 1A
shows the swivel-
base and carrying-
pulleys. This 'base
can swivel around to
the right or left, but
the pulleys remain
upright, which is
sometimes exceed-
ingly inconvenient.

The improved
swivel-base is shown
attached in Fig 2,
and detached in Fig.
2B.

It will be seen that
by its construction
a swivel of itself,
which can be set and
held by the thumb-
screw at any angle
to suit the line and give it a proper direction without dis-
torting the diagram or abraiding the line.

F. W. BACON, M. E.,

FURNISHES INSRUMENTS,
AND GIVES INSTRUCTION IN THEIR USE.

MANUFACTURERS, and others using Steam-Engines, can, by apply-
ing the INDICATOR, ascertain the condition of their Engines ; the
power required to do their work, or any portion thereof ; the economy
of fuel expended, when compared with power developed.

The undersigned makes a specialty of this branch of engineering,
and will wait on any party who desire his services.

Special attention given to the erection of Steam-Engines and
Machinery, Shafting and Belting.

Will attend to laying out works, and make plans and estimates.

Parties wishing to burn shavings, saw-dust, and other light fuels,
can have their furnaces constructed so as to consume the smoke and
gases therefrom, at a moderate cost.

F. W. BACON, Consulting Engineer,

33 Bromfield Street, Boston.

AGENT FOR

HANCOCK'S STEAM BLOWER,

The cheapest, best, and most efficient
Blower known.

NO OILING, NO SHAFTING, NO PULLIES, NO BELTING
^QV_J^ REQUIRED.

For burning screenings, re-heating in rolling mills, and hot nut-
presses it has no substitute.

Guaranteed to give entire satisfaction or no sale.

Lane's Improvement— Inside View.

ORIGINAL STEAM GAUGE Co.— BUSINESS ESTABLISHED IN 1851.
INCORPORATED IN 1854.

SOLE MANUFACTURERS OF THE

THOMPSON IMPROVED INDICATOR.

THE THOMPSON IMPROVED INDICATOR.

BOURDON STEAM GAUGE,

WITH LANE'S IMPROVEMENT.

Amsler's Polar Planimeter and the Pantograph,

36 Cliardon Street, Boston, Mass.

J. C. BIAISDELL, E. BtRT PHILIIPS, H. K. MOOBE,
Pres. Treas. Supt,

FOR

ELECTRIC LIGHTING UNEQUALLED.

FOR OTHER PURPOSES UNEXCELLED.

PATENT STEM PUMPS

THE STANDARD!

SEND FOR CATALOGUE.

ADDRESS

Knowles Steam-Pump Works,

44 Washington Street, Boston, Mass,

93 Liberty Street, New York,

TED STEAM PUMPS,

PUMPING MACHINERY

OF EVERY DESCRIPTION.

Send for New Illustrated Catalogue.

GEO. F. BLAKE M'FG CO.,

95 & 97 Liberty Street, New York.

44 Washington Street, Boston, Mass,

JAftYIS PATENT FUBNACE

FOR SETTING

STEA.M BOILERS.

Economy of Fuel, with increased capacity of steam-power. Like the
SIEMENS STEEL PROCESS, it utilizes the waste gases with hot air on
top of the fire. Burns all kinds of waste without a blast, including screen-
ings, wet peat, wet hops, sawdust, logwood chips, slack coal, wet oagasse,
etc. Send for circular.

JARVIS ENGINEERING CO.,

A. F. UPTON, TREASURER,

7 Oliver Street, Boston, Mass.

OVER 50,000 IN USE.

THE BEST FEEDER KNOWN FOR

STATIONARY, MARINE,

AND LOCOMOTIVE BOILERS.

AWARDED A

IMC

THE HIGHEST PRIZE,

At the Paris Exposition, 1878,

CONSUMES LESS STEAM THAN ANY
OTHER BOILER FEEDER KNOWN.

It is the Injector Perfected.

ALLSIZES LIFT WATER
25 FEET.

NO ADJUSTMENT REQUIRED FOR
VARYING STEAM PRESSURES.

BOILERS LAST LONGER

AND STEAM BETTER
WITH THE INSPIRATOR

THAN WITH A PUMP.
Manufactured by the

HANCOCK INSPIRATOR CO.,

34 BEA^OTtC STREET,
BOSTON, MASS.

jEEi>T VICTOR.I-A- STREET,
LONDON, ENG-.

Organised 1366.

J. M. ALLEN, President.

W. B. FRANKLIN, J. B. PIERCE,

Vice-President. Secretary.

1852.

J. H, & T, CUNNINGHAM, Proprietors,

MANUFACTURERS OF

BOSTON, MASS.

OFFICE, WAREHOUSE,

At Works, Charlestown, Mass. No. 109 Milk Street, Boston.

MANUFACTURERS OF

Turret, Screw-Chasing-

HAND LATHES,

CHUCKS, AND SLIDE-RESTS.

OF ALL SIZES,

VALVE MILLING MACHINES, SHAFTING,
HANGERS, AND PULLEYS,

No. 84 KING-STON STREET
BOSTON, MASS.

BENJ. F. RADFORD, Supt. CHAS. R. MCLEAN, Treas.

BOSTON, MASS.

1854.

SOLE MANUFACTURERS OF

WITH

LANE'S IMPROVEMENT.

—

WATER GAUGES,

COMPOUND GAUGES,

HYDEAULIC GAUGES,

COMBINATION GAUGES,

VACUUM GAUGES,
MERCURIAL SIPHON GAUGES.

Also exclusive Manufacturers of

THOMPSON IMPROVED and RICHARDS STEAM-
ENGINE INDICATORS,

GAUGE COCKS,

LONG'S SALINOMETER POTS,

PYROMETERS, HYDROMETERS,

HIGH AND LOW GRADE THERMOMETERS,

SALINOMETER THERMOMETERS,

LANE'S LOW- WATER AND ALARM GAUGES,

CLOCKS, REVOLUTION COUNTERS,

HUSSEY SPEED INDICATORS,

MERCURY COLUMNS,

And all kinds of

STEAMSHIP INSTRUMENTS.

Established 1864.

WILLIAM A. HARRIS,

MANUFACTURER OF

WITH

mm rmnm niriovsinin.

ALSO

HEAVY AND LIGHT

IRON AND BRASS CASTINGS,

R. I.

'»* Any book in this Catalogue sent free by mail on receipt of price,

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Howstring, Lenticular, and other Trusses, from fixed and
moving loads, with practical applications and examples, for
the use of Students and Engineers. 87 wood-cut illustra-
tions. Third edition. 8 vo, cloth 350

UNIVERSITY OF CALIFORNIA
LIBRARY

Due two weeks after date.

-•tr. f.

30m-7,'12

THE UNIVERSITY OF CALIFORNIA LIBRARY

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Full text of "A treatise on the Richards steam-engine indicator, with directions for its use"

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